Western epistemology runs like a relay: Plato distrusts the senses; René Descartes doubts everything to find certainty; John Locke and David Hume ground knowledge in experience and end in scepticism; Immanuel Kant argues the mind shapes what it knows.
The Indian tradition asks a different question. In the Bṛhadāraṇyaka Upaniṣad the highest knowledge (vidyā) is not information about objects but the realization of the knower itself — and that knowledge liberates. Follow the whole relay in What Can We Know?.
Thinkers & Authors
44Uddālaka Āruṇi
Upanishadic teacher who instructed his son Śvetaketu with salt in water and the seed of a banyan, ending each lesson — “tat tvam asi”, that thou art.
Yājñavalkya
The boldest sage of the Upanishads, who taught that the Self (ātman) is the unseen seer, describable only as “neti neti” — not this, not this.
Gārgī Vācaknavī
The woman philosopher who challenged Yājñavalkya at King Janaka’s court with questions about what the universe is “woven on” — pressing him until he warned that her head would fall off, then returning with two questions “like arrows”. One of the earliest named women philosophers in history.
Maitreyī
Yājñavalkya’s wife, “a discourser on Brahman”, who asked whether all the wealth in the world could make her immortal — and, refusing her share of his property, received instead his teaching that all love is love of the Self.
Sophocles
The Athenian tragedian of Oedipus and Antigone — the poet of human blindness, unbending will and the collision of laws — whom Aristotle took as the model of tragedy.
Socrates
The Athenian gadfly who wrote nothing, claimed to know nothing, questioned everyone — and was put to death for it, becoming philosophy’s martyr.
Pāṇini
The grammarian of ancient Gandhāra whose Aṣṭādhyāyī — 4,000 rules generating the whole of Sanskrit — is the most rigorous description of any language before modern linguistics, and one of the great intellectual achievements of antiquity.
Plato
Socrates’ student and Aristotle’s teacher, author of the dialogues, founder of the Academy, and the philosopher of the Forms — of whom Whitehead said all Western philosophy is a series of footnotes.
Aristotle
Plato’s greatest student and tutor of Alexander the Great, who founded logic, systematized biology, ethics and politics, and brought the Forms down to earth.
Kauṭilya (Cāṇakya)
The Brahmin strategist who, by tradition, made Candragupta Maurya emperor and wrote the Arthaśāstra — the ancient world’s most comprehensive treatise on statecraft, economics, law, diplomacy, espionage and war. India’s Machiavelli, two thousand years before Machiavelli.
Zhuangzi
The wittiest of Chinese philosophers — the butterfly dreamer, sceptic, and teller of tales — who mocked fixed perspectives and taught the free and easy wandering of a mind attuned to the Dao.
Jaimini
The sage credited with the Mīmāṃsā Sūtras, the founding text of Vedic hermeneutics — and, in legend, a disciple of Vyāsa who heard the Mahābhārata from his master.
Kaṇāda
The founder of Vaiśeṣika and traditional author of the Vaiśeṣika Sūtras — the sage remembered as India’s first atomist, who taught that everything perceptible is built from eternal, indivisible particles.
Gautama Akṣapāda
The founder of the Nyāya school and traditional author of the Nyāya Sūtras — the first systematic Indian treatise on logic, knowledge and debate. Legend gave him eyes in his feet.
Nāgārjuna
Founder of the Madhyamaka (“Middle Way”) school of Buddhism, who argued that all things are empty (śūnya) of independent existence — including emptiness itself.
Patañjali
The compiler of the Yoga Sūtras — 196 terse aphorisms that define yoga as the stilling of the mind — honoured by tradition also as the grammarian of the Great Commentary on Pāṇini and as an incarnation of the serpent Ādiśeṣa.
Kundakunda
The most revered Digambara Jain teacher — author of the Samayasāra, which distinguishes the absolute standpoint, from which the soul is pure consciousness untouched by karma, from the conventional standpoint, from which it is bound.
Asaṅga
Co-founder of Yogācāra Buddhism, who after twelve years of fruitless meditation found the future Buddha Maitreya in a wounded dog — and wrote the great maps of the bodhisattva path and of consciousness.
Vasubandhu
The 4th–5th century Buddhist philosopher who wrote the definitive summary of Abhidharma — and then, converted by his brother Asaṅga, became co-founder of Yogācāra, arguing that the world we experience is “representation only”.
Buddhaghosa
The 5th-century Indian monk who went to Sri Lanka and translated and systematised the Theravāda commentaries — author of the Visuddhimagga, “The Path of Purification”, the definitive map of Theravāda doctrine and meditation.
Bhartṛhari
The 5th-century philosopher of language who taught that ultimate reality is the Word (śabda-brahman), that meaning flashes forth as a whole (sphoṭa), and that all knowledge is shot through with language — and, by tradition, the poet of the Three Centuries on love, worldly wisdom and renunciation.
Dignāga
The founder of Buddhist logic and epistemology — only perception and inference give knowledge, perception grasps bare particulars, concepts are constructions, and words mean by excluding (apoha). He revolutionised the logic of every Indian school.
Dharmakīrti
The 7th-century Buddhist logician who perfected Dignāga’s epistemology — proving momentariness, refuting a creator God and the Veda’s authority, and defining knowledge by its reliability — the most formidable philosophical opponent the Hindu schools ever faced.
Kumārila Bhaṭṭa
The 7th-century Mīmāṃsā philosopher who turned Vedic ritual hermeneutics into a full philosophy — defending the authorless Veda, the self-validity of knowledge and a realist world against the Buddhists, and arguing that no creator God is needed.
Ādi Śaṅkara
The great systematizer of Advaita (non-dual) Vedānta — Brahman alone is real, the world is māyā, and the individual self is none other than Brahman.
Udayana
The great Nyāya philosopher of Mithilā who gave Indian philosophy its classic proofs of God’s existence, defended the reality of the self against the Buddhists, and closed the classical age of Nyāya-Vaiśeṣika.
Avicenna (Ibn Sīnā)
Persian polymath — physician, metaphysician, logician — whose Canon of Medicine was taught in Europe for 500 years and whose distinction between essence and existence reshaped philosophy in Islam and the Latin West.
Al-Ghazālī
Theologian, jurist and mystic whose Incoherence of the Philosophers attacked Avicenna’s Aristotelianism, anticipated Hume on causation, and whose spiritual autobiography records a crisis of doubt.
Hemacandra
The Jain polymath of 12th-century Gujarat — grammarian, poet, logician, lexicographer, historian and royal adviser — called “the omniscient of the Kali age”, who persuaded a king to ban animal slaughter.
Averroes (Ibn Rushd)
Andalusian judge and philosopher — “the Commentator” on Aristotle — who defended philosophy against al-Ghazālī and argued that reason and revelation cannot contradict each other.
Jñāneśvar
The 13th-century Marathi saint-poet who, at about twenty, wrote the Jñāneśvarī — a 9,000-verse commentary on the Bhagavad Gītā in Marathi that founded Marathi literature and the Vārkarī devotional tradition — and entered living samādhi at twenty-one.
Gaṅgeśa Upādhyāya
The 14th-century logician of Mithilā who founded Navya-Nyāya, the “New Logic”, in his Tattvacintāmaṇi — a technical language of such precision that it became the common idiom of Indian scholarship for five centuries.
Michel de Montaigne
The inventor of the essay, who made himself the subject of his book — sceptical, curious, tolerant, candid — and asked, “Que sais-je?” — What do I know?
Miguel de Cervantes
Soldier, captive, tax collector and the father of the modern novel — whose Don Quixote made a deluded old knight and his earthy squire the most famous pair in literature.
René Descartes
The father of modern philosophy, who doubted everything that could be doubted and found one thing that could not — that he himself was thinking.
John Milton
English poet, polemicist and revolutionary whose Paradise Lost — written blind, after the defeat of his cause — retells the Fall of Man to “justify the ways of God to men”, and gave literature its most magnificent rebel, Satan.
John Locke
Father of British empiricism and of liberalism — the mind begins as a blank slate, and government rests on the consent of the governed.
David Hume
The great Scottish sceptic who showed that causation, the self, and induction cannot be justified by reason — and that reason is, and ought only to be, the slave of the passions.
Immanuel Kant
The philosopher who tried to end the war between rationalism and empiricism by asking what the mind itself contributes to experience — the “Copernican revolution” in philosophy.
Johann Wolfgang von Goethe
Germany’s greatest writer — poet, novelist, dramatist, scientist and statesman — whose Faust is the modern myth of the striving soul, and whose life was itself treated as a work of art.
Ramana Maharshi
The silent sage of Arunachala (1879–1950), who at sixteen experienced his own death and the deathless Self, and taught one practice above all — self-inquiry, “Who am I?” — the simplest and most direct path of Advaita.
Sarvepalli Radhakrishnan
The philosopher-statesman who presented Indian philosophy to the West as a living tradition — Oxford’s Spalding Professor of Eastern Religions, author of Indian Philosophy, and India’s second President. Teachers’ Day is his birthday.
Ludwig Wittgenstein
The Viennese-Cambridge philosopher who twice transformed philosophy — first by mapping the limits of what language can say (Tractatus), then by showing that meaning is use in the countless “language games” of ordinary life (Philosophical Investigations).
Jiddu Krishnamurti
The philosopher raised by the Theosophists to be a “World Teacher”, who renounced the role in 1929 — “truth is a pathless land” — and spent sixty years teaching that freedom comes only from seeing the movement of one’s own mind, without authority, method or guru.
Works
24The Upaniṣads
The philosophical dialogues that close the Vedas (c. 800–200 BCE) — forest teachings in which kings, priests, women and a boy at Death’s door ask what the Self is, what Brahman is, and how to be free. The source of Vedānta, and of almost every later Indian idea about the self.
Bṛhadāraṇyaka Upaniṣad
The “Great Forest” Upanishad, oldest and longest, home of Yājñavalkya’s debates, the teaching to Maitreyī, and “neti neti”.
Chāndogya Upaniṣad
One of the oldest Upanishads, famed for Uddālaka’s teaching to Śvetaketu — tat tvam asi — and Satyakāma’s honest answer about his birth.
Taittirīya Upaniṣad
The Upaniṣad of the five sheaths and the graduation address — it defines Brahman as “truth, knowledge, infinity”, peels away the layers of the self from food to bliss, measures the bliss of Brahman, and tells departing students “Treat your mother as a god.”
Kaṭha Upaniṣad
The story of the boy Naciketas, who goes to the house of Death and asks what happens after death — receiving the teaching of the immortal Self.
Kena Upaniṣad
The “By whom?” Upaniṣad — by whom is the mind sent forth, the breath set going, speech uttered? Its answer is the paradox that Brahman is known only by those who know they do not know it — and a story of the gods humbled by a blade of grass.
Oedipus the King
Sophocles’ tragedy of the king who hunts down the murderer of his predecessor — and discovers that he himself killed his father and married his mother. Aristotle’s model of the perfect tragedy.
Muṇḍaka Upaniṣad
The Upaniṣad of the “shaven head” — it distinguishes the “lower knowledge” of the Vedas and sciences from the “higher knowledge” of the imperishable, compares ritual to leaky boats, gives the image of two birds on one tree, and India its national motto, “Truth alone triumphs”.
Śvetāśvatara Upaniṣad
The most theistic of the principal Upaniṣads — it identifies Brahman with Rudra-Śiva, a personal Lord to be loved, blends Vedānta with early Sāṃkhya and Yoga, and first uses the words māyā and bhakti in their later senses.
The Apology of Socrates
Plato’s account of Socrates’ defence speech at his trial in 399 BCE — a manifesto for the philosophical life.
The Republic
Plato’s great dialogue on justice — in the soul and in the city — containing the philosopher-kings, the Allegory of the Cave, and the banishment of the poets.
The Nāṭyaśāstra
Bharata’s encyclopaedia of the performing arts — theatre, dance, music, costume, architecture, and the theory of rasa — called the “fifth Veda”, composed for all classes of people. The foundation of Indian aesthetics.
The Nyāya Sūtras
The root text of Indian logic — about 530 aphorisms on the means of valid knowledge, the structure of argument, the art of debate and its dishonest tricks, and the self, the world and liberation.
The Pañcatantra
The ancient Indian book of animal fables written to teach princes the art of practical wisdom (nīti) — the jackals Karaṭaka and Damanaka, the monkey and the crocodile, the lion and the hare — translated into more languages than almost any book except the Bible.
Māṇḍūkya Upaniṣad
The shortest Upaniṣad — twelve verses on the syllable Oṃ and the four states of consciousness, waking, dreaming, deep sleep and the “fourth” (turīya), the pure Self. Said to be enough, by itself, for liberation.
The Questions of King Milinda
A dialogue between the Indo-Greek king Menander and the Buddhist monk Nāgasena — the chariot argument for no-self, the flame of rebirth, and a Greek king’s sharp questions answered with Indian wit. A meeting of Greece and India in the 2nd century BCE.
Mūlamadhyamakakārikā
Nāgārjuna’s 450 verses in 27 chapters — the founding text of Madhyamaka, which examines causation, motion, the self, time and nirvāṇa, and shows that nothing has intrinsic existence; everything is empty because everything is dependent.
Tattvārtha Sūtra
Umāsvāti’s “Manual of the Meaning of the Reals” — the first Sanskrit summary of Jain philosophy, 350 sūtras accepted by both Digambaras and Śvetāmbaras, covering knowledge, souls, the universe, karma, ethics and liberation.
The Yoga Sūtras
Patañjali’s 196 aphorisms — the root text of classical Yoga — which define yoga as the stilling of the mind’s fluctuations, diagnose the afflictions that cause suffering, set out the eight limbs of practice, and end in the “isolation” of pure consciousness.
Don Quixote
Cervantes’s comic masterpiece about a country gentleman driven mad by chivalric romances, who sets out as a knight-errant with his squire Sancho Panza — often called the first modern novel and the greatest ever written.
Critique of Pure Reason
Kant’s masterwork, asking what reason can know without experience — and answering that it can know the forms of all possible experience, but nothing beyond.
Prolegomena to Any Future Metaphysics
Kant’s short, clearer restatement of the first Critique, where he credits Hume with waking him from his dogmatic slumber.
Faust
Goethe’s two-part dramatic poem of the scholar who wagers his soul with Mephistopheles that no moment of pleasure will ever satisfy him — the defining myth of modern restless striving.
Beyond Good and Evil
Nietzsche’s “prelude to a philosophy of the future” — an attack on the prejudices of philosophers, from Plato to Kant, and a sketch of the free spirit.
Ideas
12Anekāntavāda
The Jain doctrine that reality is many-sided — that every thing has infinite aspects and every statement captures only one, so that truth requires holding many viewpoints together. Expressed in the parable of the blind men and the elephant and formalised in the sevenfold logic of syādvāda.
Pratītyasamutpāda (Dependent Origination)
The Buddha’s central insight — “when this exists, that comes to be; when this ceases, that ceases.” Nothing exists independently; everything arises from conditions. Applied to suffering, it becomes the twelve-linked chain from ignorance to death.
The Forms
Plato’s eternal, perfect, unchanging realities — Beauty itself, Justice itself, the Good — of which the things we see are imperfect copies.
Śūnyatā (Emptiness)
Emptiness — the Mahāyāna teaching that all things lack intrinsic, independent existence (svabhāva), because they arise in dependence on causes, parts and concepts. Not nothingness, but the openness that makes change and freedom possible.
Rasa
The Indian theory of aesthetic experience — the “flavour” or “relish” that art evokes in the audience. Bharata named eight rasas; Abhinavagupta added peace and explained rasa as the self tasting its own consciousness through universalised emotion.
Māyā
The power of appearance — in Advaita, the cosmic illusion by which the one Brahman appears as a world of many things.
Cogito, ergo sum
I think, therefore I am — the one certainty Descartes found after doubting everything else.
The Problem of Induction
No non-circular argument shows that the future will resemble the past — yet all science and daily life depend on it.
Hume's Fork
Every meaningful claim is either a relation of ideas (certain but empty) or a matter of fact (informative but uncertain) — metaphysics is neither.
Synthetic a priori
Judgments that are informative about the world yet knowable independently of experience. Kant’s master question was how they are possible.
The Thing-in-Itself
Reality as it is independently of how it appears to us — for Kant, thinkable but never knowable.
The Copernican Revolution
Kant’s reversal — instead of the mind conforming to objects, objects must conform to the mind’s forms of knowing.
Schools & Movements
18Vedānta
“The end of the Veda” — the schools that interpret the Upanishads, Bhagavad Gītā and Brahma Sūtras to understand Brahman, the Self, and liberation.
Cārvāka (Lokāyata)
India’s materialist school — only perception is knowledge, only matter is real, there is no soul, no rebirth, no karma and no God, and the purpose of life is pleasure. Its own books are lost; we know it through the furious refutations of every other school.
Jainism
The ancient Indian tradition of the Jinas — radical non-violence toward every living being, a soul weighed down by karmic matter, the “many-sidedness” of truth, and liberation by self-discipline without a creator God. Small in numbers, immense in influence.
Buddhism
The tradition founded by the Buddha — suffering, impermanence, no-self, and the path to nirvāṇa — later dividing into Theravāda, Mahāyāna (Madhyamaka, Yogācāra) and Vajrayāna.
Platonism
The tradition descending from Plato — eternal Forms, an immortal soul, and a reality higher than the senses — from the Academy through Neoplatonism to Christian theology.
Mīmāṃsā
The school of Vedic interpretation — the hermeneutics of ritual and duty that treated the Veda as eternal and authorless, defended the self-validity of knowledge, denied a creator God, and developed theories of language, meaning and law that shaped all of Hindu jurisprudence.
Theravāda and the Abhidharma
The oldest surviving school of Buddhism — the Pāli Canon, the arhat ideal, and the Abhidhamma analysis of experience into momentary ultimate realities — living today in Sri Lanka, Myanmar, Thailand, Laos and Cambodia.
Nyāya
India’s great school of logic and epistemology — the theory of valid knowledge (pramāṇa), the five-membered syllogism, the catalogue of fallacies, realist metaphysics, and the most famous arguments for God in Indian philosophy. Its later form, Navya-Nyāya, became the technical language of all Indian scholarship.
Vaiśeṣika
India’s school of natural philosophy and atomism — reality analysed into six (later seven) categories, the world built from eternal, indivisible atoms of earth, water, fire and air, combined by an unseen moral force. Merged with Nyāya, it gave Indian realism its map of what exists.
Yoga (darśana)
The classical school of Patañjali — Sāṃkhya’s dualism of consciousness and nature, plus a God and a practical method — defining yoga as “the stilling of the fluctuations of the mind” and mapping the eight limbs from ethics to absorption.
Madhyamaka
Nāgārjuna’s school of emptiness — nothing has intrinsic existence (svabhāva), all things are empty because they arise in dependence, and even emptiness is empty. Its dialectic dismantles every view, and it became the summit of Tibetan Buddhist philosophy.
Yogācāra
The “mind-only” school of Mahāyāna Buddhism, founded by Asaṅga and Vasubandhu — the world we experience is a construction of consciousness, carried by a “storehouse” of karmic seeds; awakening is the transformation of the basis of consciousness itself.
Advaita Vedānta
Non-dualist Vedānta — Brahman alone is real, the world is appearance (māyā), and the self is identical with Brahman.
Scholasticism
The method and philosophy of the medieval universities — rigorous disputation, the reconciliation of faith and reason, and the absorption of Aristotle into Christian, Jewish and Islamic thought.
Continental Rationalism
The seventeenth-century conviction that reason alone, unaided by the senses, can reach certain knowledge of the deepest truths.
The Enlightenment
The eighteenth-century movement that put reason, science, tolerance and individual liberty at the centre of human affairs — “Sapere aude!”
British Empiricism
The view that all knowledge comes from experience — the mind begins as a blank slate on which the senses write.
Phenomenology
Husserl’s method of describing experience exactly as it appears — “to the things themselves!” — which Heidegger and Sartre turned toward existence.
Debates
2Is There a Self? Nyāya vs. the Buddhists
The thousand-year Indian debate between Nyāya logicians, who argued that memory and recognition prove an enduring self, and Buddhist philosophers, who held that a person is a stream of momentary events.
Rationalism vs. Empiricism
The great quarrel of early modern philosophy — does knowledge come from reason or from experience? Kant tried to end it.
Characters
1Great Scenes
5The Death of Socrates
In prison, on his last day, Socrates argues for the immortality of the soul, drinks the hemlock calmly, and asks that a cock be offered to Asclepius.
The Allegory of the Cave
Prisoners chained since birth see only shadows on a cave wall; one is freed, dragged into the sunlight, and returns to tell the others — who would kill him if they could.
The Blinding of Gloucester
Betrayed by Edmund, Gloucester is tied to a chair and blinded by Cornwall while Regan watches — and learns in the same instant that Edgar was innocent.
Naciketas at the House of Death
Given away by his angry father, the boy Naciketas waits three days at Death’s door, and refuses all the riches Yama offers until Death tells him what lies beyond.
Tat Tvam Asi — Salt in Water
Uddālaka tells his son Śvetaketu to dissolve salt in water and taste it — invisible, yet everywhere — “that is the Self; that thou art.”
Great Questions
3What Are the Limits of the Human Mind?
Can reason know everything — or are there things the mind can never reach? From the Upanishads’ unknowable knower to Kant’s boundary and Wittgenstein’s silence.
What Is Beauty — and What Is Art For?
From Plato’s ladder of love and Aristotle’s catharsis to Kant’s disinterested pleasure, Schopenhauer’s music and Nietzsche’s Apollo and Dionysus.
What Can We Know?
The relay race of epistemology — from Plato’s Cave to Kant’s categories, via Descartes’ demon and Hume’s billiard balls.
Lines to Remember
36 quotationsThe unexamined life is not worth living.
ὁ δὲ ἀνεξέταστος βίος οὐ βιωτὸς ἀνθρώπῳ
Context & when to use it
At his trial, refusing to go into exile and keep quiet — a life without philosophical examination is no life for a human being.
The founding sentence of philosophy. For reflection, self-knowledge, intellectual courage.
I am wiser than this man; for neither of us really knows anything fine and good, but this man thinks he knows something when he does not, whereas I, as I do not know anything, do not think I do either.
Context & when to use it
After questioning a politician reputed to be wise.
The authentic source of “I know that I know nothing” — use against overconfidence and the Dunning–Kruger effect.
⚠ The slogan “I know that I know nothing” is a later compression; Socrates’ actual claim is more modest.
They see only their own shadows, or the shadows of one another, which the fire throws on the opposite wall of the cave.
Context & when to use it
For illusion, propaganda, echo chambers, mistaking appearance for reality.
Until philosophers are kings, or the kings and princes of this world have the spirit and power of philosophy… cities will never have rest from their evils.
Context & when to use it
For the relation of wisdom and power; technocracy debates.
It is owing to their wonder that men both now begin and at first began to philosophize.
Context & when to use it
Plato said the same in the Theaetetus (155d) — philosophy begins in wonder.
For curiosity as the root of philosophy and science.
What then is time? If no one asks me, I know; if I wish to explain it to one who asks, I know not.
Quid est ergo tempus? Si nemo ex me quaerat, scio; si quaerenti explicare velim, nescio.
Context & when to use it
For any concept we use easily but cannot define.
There are no facts, only interpretations.
Context & when to use it
Against positivism — “facts is precisely what there is not, only interpretations.”
For perspectivism; careful — Nietzsche is not saying anything goes.
⚠ From an unpublished notebook, not a book he finished.
Life can only be understood backwards; but it must be lived forwards.
Context & when to use it
Reflection always comes after; we must act before we understand.
For decisions under uncertainty, regret, the limits of hindsight.
From the unreal lead me to the real; from darkness lead me to light; from death lead me to immortality.
असतो मा सद्गमय। तमसो मा ज्योतिर्गमय। मृत्योर्मा अमृतं गमय॥
Context & when to use it
The pavamāna mantra, chanted for purification.
For the spiritual journey from ignorance to knowledge; a prayer that fits any tradition.
This Self is not this, not this. It is ungraspable, for it is not grasped; indestructible, for it is not destroyed; unattached, for it does not attach itself.
स एष नेति नेत्यात्मा
Context & when to use it
For apophatic thought — what cannot be described, only negated (compare negative theology).
You cannot see the seer of seeing; you cannot hear the hearer of hearing; you cannot think the thinker of thinking; you cannot know the knower of knowing.
Context & when to use it
For the subject that cannot be an object — compare Kant’s transcendental “I” and Wittgenstein’s eye that does not see itself.
Arise! Awake! Approach the great ones and learn. Sharp as the edge of a razor, hard to cross — the path is difficult, so the sages say.
उत्तिष्ठत जाग्रत प्राप्य वरान्निबोधत। क्षुरस्य धारा निशिता दुरत्यया दुर्गं पथस्तत्कवयो वदन्ति॥
Context & when to use it
Vivekananda’s favourite verse.
For awakening, effort, the difficulty of the spiritual or intellectual path.
I freely admit that it was the remembrance of David Hume which, many years ago, first interrupted my dogmatic slumber.
Context & when to use it
Kant’s tribute to the sceptic who forced him to rethink everything.
When someone’s comfortable certainties have just been shaken — or to credit an opponent who made you think.
Thoughts without content are empty, intuitions without concepts are blind.
Gedanken ohne Inhalt sind leer, Anschauungen ohne Begriffe sind blind.
Context & when to use it
The whole Kantian synthesis in eight words — rationalism without senses is empty; empiricism without concepts is blind.
The perfect one-liner for “theory vs. experience” arguments.
I think, therefore I am.
Je pense, donc je suis.
Context & when to use it
The foundational certainty of modern philosophy; for self-knowledge and doubt.
If you would be a real seeker after truth, it is necessary that at least once in your life you doubt, as far as possible, all things.
Context & when to use it
For methodical doubt and intellectual honesty.
Commit it then to the flames, for it can contain nothing but sophistry and illusion.
Context & when to use it
The famous end of the Enquiry — any book that contains neither mathematical reasoning nor experimental reasoning about facts.
Against empty metaphysics, jargon, unfalsifiable claims.
A wise man proportions his belief to the evidence.
Context & when to use it
For rational belief, scepticism about extraordinary claims.
I dine, I play a game of back-gammon, I converse, and am merry with my friends; and when after three or four hours’ amusement, I would return to these speculations, they appear so cold, and strained, and ridiculous.
Context & when to use it
Hume’s cure for sceptical despair — nature and company.
When philosophy has gone too far; for common sense and conviviality.
Let us then suppose the mind to be, as we say, white paper, void of all characters, without any ideas. How comes it to be furnished?… To this I answer, in one word, from experience.
Context & when to use it
For empiricism and nurture over nature.
The owl of Minerva spreads its wings only with the falling of the dusk.
Die Eule der Minerva beginnt erst mit der einbrechenden Dämmerung ihren Flug.
Context & when to use it
Philosophy understands an age only when it is ending.
For hindsight; why theory lags behind history.
The true is the whole.
Das Wahre ist das Ganze.
Context & when to use it
For holism against piecemeal truths.
Talent hits a target no one else can hit; genius hits a target no one else can see.
Context & when to use it
For genius and vision.
The limits of my language mean the limits of my world.
Die Grenzen meiner Sprache bedeuten die Grenzen meiner Welt.
Context & when to use it
The Tractatus on the subject as the limit of the world.
For how vocabulary shapes thought, and for learning languages.
Whereof one cannot speak, thereof one must be silent.
Wovon man nicht sprechen kann, darüber muss man schweigen.
Context & when to use it
The last proposition of the book — after throwing away the ladder.
For the limits of argument, the ineffable, or ending a pointless dispute.
What is your aim in philosophy? — To show the fly the way out of the fly-bottle.
Context & when to use it
Philosophy as therapy for confusions created by language.
For dissolving rather than solving a problem.
If you tried to doubt everything you would not get as far as doubting anything. The game of doubting itself presupposes certainty.
Context & when to use it
Against radical scepticism.
Brevity is the sister of talent.
Краткость — сестра таланта.
Context & when to use it
For editing, writing, and speaking.
What is here may be found elsewhere; what is not here is nowhere.
yad ihāsti tad anyatra yan nehāsti na tat kvacit
Context & when to use it
For a work that contains a world.
The syllogism he had learnt — “Caius is a man, men are mortal, therefore Caius is mortal” — had always seemed to him correct as applied to Caius, but certainly not as applied to himself.
Context & when to use it
Dying, Ivan Ilyich discovers that logic does not make death believable.
For the gap between knowing and realizing; Heidegger’s “one dies” versus “I die”.
There are more things in heaven and earth, Horatio, than are dreamt of in your philosophy.
Context & when to use it
After seeing the Ghost, to his rationalist university friend.
Against narrow rationalism or scientism; for the limits of any system — Kant’s noumena in one line.
⚠ “Your philosophy” means philosophy in general, not Horatio’s personal philosophy.
How terrible it is to know, when knowledge brings no profit to the knower.
Context & when to use it
For unwelcome truths and the burden of knowledge.
Consider your origin — you were not made to live like brutes, but to follow virtue and knowledge.
fatti non foste a viver come bruti, ma per seguir virtute e canoscenza
Context & when to use it
Ulysses urges his old companions on their last voyage beyond the known world — which ends in shipwreck.
For the thirst for knowledge — and its risks. Primo Levi recited it in Auschwitz.
Look, your worship, those things over there aren’t giants, they’re windmills, and what seem to be their arms are the sails.
Context & when to use it
For the realist’s reply to the idealist — and for tilting at windmills.
Grey, dear friend, is all theory, and green the golden tree of life.
Grau, teurer Freund, ist alle Theorie, und grün des Lebens goldner Baum.
Context & when to use it
For life over abstraction — with a wink about who says it.
⚠ Spoken by the devil, mocking a student — not Goethe’s sincere verdict on theory.
The play’s the thing wherein I’ll catch the conscience of the king.
Context & when to use it
For art as a mirror that reveals guilt.
Sententiae
phrases in the originalGnōthi seauton
Origin. Inscribed in the forecourt of the Temple of Apollo at Delphi; Socrates made it the charge of his philosophy (Plato, Phaedrus 229e, Charmides 164d). — Socrates
⚠ Originally probably meant “know your place — you are mortal, not a god”, not introspection.
For self-knowledge, humility, the starting point of wisdom.
Aporia
Origin. The state Socrates leaves his partners in at the end of the early dialogues — they realize they don’t know what they thought they knew. — Socrates
For honest bewilderment as the beginning of thought.
Hen oida hoti ouden oida
Origin. A later Greek slogan summarizing Socrates in Plato’s Apology (21d). — Socrates
⚠ Socrates never says this in Plato. His claim is subtler — he does not think he knows what he does not know.
For intellectual humility — and for correcting someone who quotes it as Socrates’ exact words.
Cogito, ergo sum
Origin. Descartes, first in French (“je pense, donc je suis”, Discourse on Method, 1637), then in Latin in the Principles of Philosophy (1644). — René Descartes
⚠ The Meditations never use this formula — there it is “ego sum, ego existo” (I am, I exist). Augustine had argued “si fallor, sum”.
For the one certainty that survives doubt; the birth of modern subjectivity.
Tabula rasa
Origin. Roman wax tablets were scraped smooth to be reused. The image of the mind as a blank tablet goes back to Aristotle (De Anima III.4); Locke’s “white paper” made it the emblem of empiricism. — John Locke
⚠ Locke himself does not use the Latin phrase in the Essay; he says “white paper”.
For nurture versus nature, fresh starts, empiricism.
Sub specie aeternitatis
Origin. Spinoza, Ethics V — the highest knowledge sees things not in time but as following necessarily from God’s eternal nature. — Baruch Spinoza
For seeing one’s troubles from the widest possible perspective.
Amicus Plato, sed magis amica veritas
Origin. A medieval Latin compression of Aristotle, Nicomachean Ethics I.6 — “though both are dear, piety requires us to honour truth above our friends.” — Aristotle
For disagreeing with a teacher or ally out of honesty.
Das Ding an sich
Origin. Kant, Critique of Pure Reason — reality as it is independent of how it appears to us. — Immanuel Kant
For what lies beyond appearances and models.
Neti neti
Origin. Bṛhadāraṇyaka Upaniṣad 2.3.6 and Yājñavalkya’s teachings (4.2.4, 4.5.15). — Yājñavalkya, Bṛhadāraṇyaka Upaniṣad
For the via negativa — reaching the absolute by negating every description.
Satyam eva jayate
Origin. Muṇḍaka Upaniṣad 3.1.6 — the national motto of India, inscribed beneath the Lion Capital emblem.
For integrity and truth over expediency.
Asato mā sad gamaya
Origin. Bṛhadāraṇyaka Upaniṣad 1.3.28 — continued “from darkness to light, from death to immortality.” — Bṛhadāraṇyaka Upaniṣad
As a prayer for truth and understanding.
Uttiṣṭhata jāgrata
Origin. Kaṭha Upaniṣad 1.3.14 — continued “approach the great and learn”. Vivekananda’s call to India. — Kaṭha Upaniṣad
For awakening, effort, self-improvement.
Explore Next
related by shared connectionsGauḍapāda
The earliest systematic teacher of Advaita Vedānta, whose verses on the Māṇḍūkya Upaniṣad taught that nothing has ever really been born — the waking world is like a dream, and the one consciousness only seems to become many.
What Is the Self? — The Indian Argument
Three thousand years of Indian argument about the “I” — from the Upaniṣads’ Self that is Brahman, through the Buddha’s no-self, the Jain soul, the Nyāya substance, Sāṃkhya’s witness, to Ramana’s “Who am I?” and Ambedkar’s social self.
What Is the Self?
From ātman to anattā, from the cogito to the bundle, from Kierkegaard’s task of becoming oneself to Sartre’s nothingness.
Does God Exist?
The proofs, the refutations, the wagers and the leaps — the great argument about God from the Upanishads to Nietzsche.
How Is the Mind Related to the Body?
Witness-consciousness and matter, the soul as form, two substances, one substance, Dasein — the mind–body problem across civilizations.
Georg Wilhelm Friedrich Hegel
The philosopher of Spirit and dialectic, for whom reality is a rational process working itself out through contradiction in history — “the real is the rational”.