Chapter 101
The senses and sensation; perception; the reliability of the senses.
335 passages · 105 principal · Covers the 49 volumes of primary texts
The idea of sense covers the whole traffic between the mind and the world it does not make: how external things act on eye, ear, tongue and skin; what a sensation is once it has been received; what part the senses play in memory, imagination and knowledge; and whether what they report can be trusted. It is a great idea for these books because nearly every other inquiry passes through it. The philosopher who asks what can be known, the physician who asks what can be shown, the poet who asks what is real, and the moralist who asks what should be desired all meet the senses at the outset. They must accept them as witnesses, cross-examine them, or set them aside.
The moderns in this collection are the ones who try hardest to say how sensation happens. Hobbes holds that external bodies press upon the organs and that the motion this sets up, carried inward, appears to us as fancy1,2. Light, sound and odour are on his account nothing in the object but motion3. He mocks the scholastic doctrine that things send off visible and audible “species” which pass through sense to common sense, fancy and judgment4,5. Descartes likewise explains how light, sounds and tastes impress ideas on the brain through the organs6. Berkeley’s Hylas states the received modern view that impressions travel as vibrations along the nerves to the brain7, though Berkeley allows the dependence of perception on organs only in order to dispute what follows from it8. Pascal finds warmth, sound and light at once material and mysterious, a mere touching of the nerves9. Hume reports the opposite hypothesis, that sensations are excited by the volition of God rather than by agitated organs10. Burke carries the mechanism into the particular senses. He explains the sublime by the tension of the eye’s fibres before uniform objects or in darkness11,12. Sweetness, for him, is the effect of smooth, round particles on the papillae of the tongue13. Darwin traces how a nerve sensitive merely to light may develop by degrees into an image-forming eye14,15.
Whatever its mechanism, sensation appears to most of these authors as something suffered. Plutarch contrasts outward sense, which must receive whatever strikes it, with mental perception, which can be directed16. Berkeley insists that seeing and smelling are passive and independent of will17. Kant makes passive receptivity the mark that separates the world of sense from the intellectual world18. Schiller describes the first condition of man as identification with a sensuous world that passively affects him19. Emerson’s child is the “fool of his senses,” commanded by every sight and sound20. The same passivity sets limits. Augustine finds the senses of the flesh slow and bounded, able to grasp syllables only as they pass21,22. Pascal observes that the senses perceive no extreme, so that too much sound or light defeats them23. Hobbes notes that only the predominant stroke on an organ is felt, as sunlight hides the stars24. Burke remarks that the sun overpowers the sight and leaves black spots behind it25. Acuity, moreover, varies. Rousseau credits the savage with extremely acute sight, hearing and smell but blunt touch and taste26. Darwin confirms the Fuegians’ sight with a telescope27 and debates whether vultures hunt by eye or by nose28. Pope sets the senses on an ascending scale and argues that man has no need of microscopic eyes29. For Hume, the perfection of eye and palate alike lies in perceiving minute differences exactly30.
From these accounts arises the question of how sense stands to thought. One tradition holds that all ideas begin in sense. Augustine already finds in memory images that each sense supplied in its own kind, images the mind can compare without present sensation31. Hobbes declares that nothing can be thought that was not first perceived32. Imagination, for him, is decaying sense, and even the sequence of our thoughts copies a sequence first given in sensation33,34. Hume makes sensation more vivid than any copy of it in memory or imagination35. He points out that the blind and deaf lack the corresponding ideas, so sensation is the only inlet36. Burke builds the universality of taste on the senses as the originals of all ideas37.
Against this tradition stand those who deny that sense alone yields knowledge. Augustine says the senses report but cannot judge. Beasts perceive as we do, but reason interprets what they bring38,39. The principles of the sciences, he adds, were conveyed by no sense at all40. Descartes criticizes the scholastic maxim outright: neither sense nor imagination gives assurance without the understanding41. Rousseau argues that sensations present things singly, and that only an active power can compare them and know that the body touched is the body seen42,43. Even Hume concedes that the powers behind nature’s operations never appear to the senses, which show only succession44,45.
Plato goes further. For him the senses are an occasion for knowledge rather than its source. Unequal sticks remind us of an equality they fall short of46, and the unchanging is grasped by mind alone47. Dante’s Beatrice teaches that men learn through sensible things, which are then digested into understanding48. Milton holds that embodied understanding must found itself on sensible things49. Berkeley turns this around, insisting that sensible things are known only by sense, never by pure intellect50.
Then comes the great controversy over trust. In the Phaedo sight and hearing are inaccurate witnesses whose use drags the soul into confusion like a drunkard51,52. Eye and ear there are full of deceit53. Marcus Aurelius calls the organs dull and easily falsely impressed54. Descartes resolves to suppose that nothing is as the senses present it, citing jaundice, distant stars and dreams55,56. Pascal pictures sense and reason deceiving each other in turn57. Kant confines sensory ideas to appearances, never things in themselves58. Bacon takes a middle path that proves fruitful. The senses give false information or none, and their reports are relative to man. Yet all natural knowledge must still be sought from them, corrected by instruments and experiment59,60. His method therefore keeps the evidence of sense as the start of progressive certainty61.
Berkeley mounts the strongest defense, and he does so by narrowing what sense is said to report. Strictly we hear only the sound, and the coach is suggested by experience62. Sight gives colours and figures, not distance63. The oar in water is truly perceived as crooked, so the error lies in the inference drawn from it64. The real things, then, are just what is seen and felt65,66. On this ground Philonous can urge Hylas to follow nature and trust his senses67. Hylas ends by seeing things “in their native forms”68. Pascal had already written that the perceptions of the senses are always true69. Rousseau reasons that because sensations arise independently of his will, their cause is outside him70. Hume answers both sides. Men instinctively take sense images for external objects. Philosophy shows that the table seems to shrink as we recede, and that nothing proves our perceptions resemble any cause, since dreams and madness produce perceptions without objects71,72,73. Belief in external existence thus rests either on instinct against reason or on reason against instinct, and in neither case on evidence74.
Yet in practice sense remains the court of appeal. The risen Christ bids the disciples handle him, for a spirit has not flesh and bones75. Horatio will not credit the ghost without “the sensible and true avouch” of his own eyes76. Harvey rests the circulation on ocular demonstration and declares that the evidence of the senses cannot be denied77,78. Hume ranks the senses above testimony, so that a doctrine contradicting them falls79. Molière shows the comic reverse: Orgon must see for himself, while Pernelle maintains that seeing should not always be believing80.
Bound up with trust is the relativity of sensible qualities. The same water feels warm to one hand and cold to the other81. Tastes differ between persons and with a distempered palate82. The microscope changes colours83. All these suggest to Berkeley that such qualities exist only in a perceiving mind84,85. Hobbes had already called colour and sound fancies of our own bodies86. Hume, writing on taste, calls colour a phantasm and grants that sweet and bitter depend on the disposition of the organs87,88. Burke presses the other implication: because organs are alike, men agree that sour is sour and sweet sweet89. Relativity to the organ may thus ground a common standard rather than dissolve one.
Literature and science both supply a rich catalogue of perception gone astray. Dante mistakes giants for towers through mist and distance until nearness corrects him90. He takes candlesticks for golden trees until the faculty serving reason can distinguish them91. Darwin finds that clear air deceives the judgment of distances, against all his habit92. Refraction, he notes, turns mud into water93. Faraday shows how bending light raises a hidden coin94. Pasteur unmasks an apparent bead as an effect of refraction95. Bacon’s New Atlantis keeps houses devoted to deceits of the senses96. Delusion is graver than illusion because it overrides plain evidence. Don Quixote sees giants where Sancho sees windmills and blames enchanters for the discrepancy97,98. He sees armies in sheep and a golden helmet in a barber’s basin99,100. His fancy even overrules touch and smell, so that coarse hair seems gold and foul breath sweet101. Sancho’s stubborn testimony, that the blanket-tossers were flesh and blood, is the voice of the senses themselves102. Jonson’s Face exploits the same uncertainty, dismissing honest witnesses as victims of “deceptio visus”103. Dream deepens the doubt. Hobbes explains why dreams are hard to tell from perception33. Calderón’s Segismund asks whether his bewildered senses can vouch for reality at all, and concludes that sense-confessed reality cannot be told from a repeated dream104,105. Macbeth wonders whether his eyes are fools of the other senses or worth all the rest106.
Among the particular senses, sight holds the first place. Augustine notes that the other senses borrow its name107. Burke finds the eye excelling touch in the extent and multiplicity of its objects, yet bound to the other senses by analogy108,109. Schiller praises eye and ear because, freed from nature’s pressure, they lead to the real through appearance110. Whitman makes eyesight a forerunner of the spiritual world that mocks all investigation111. Blindness measures this pre-eminence by its loss. Samson asks why sight should be confined to so tender an eye112. Milton’s narrator is cut off from the human face and the seasons113. Cibber’s blind boy knows the sun only by its warmth114. Shakespeare’s Gloucester learns that he stumbled when he saw, and comes to see the world “feelingly”115,116. In art the senses are both ground and rival of imagination. Burke ranks the pleasures of each sense and finds them the same in all men117. Lamb, by contrast, holds that on the stage the bodily eye spoils what reading leaves terrible118,119. Hunt says that poetic images are heard and seen by senses purified through imagination120. Goethe thinks the best pictures speak to sense in a higher language that requires understanding121.
Finally there is the moral estimate. The Bhagavad-Gita warns that unmastered senses assail the mind like a whirlwind on a ship122. Marcus Aurelius would separate sense impressions from the ruling faculty123. Thomas à Kempis bids that all the senses be restrained under discipline124. Augustine confesses that the eyes’ love of forms and light entwines the soul all day125. Epictetus, more temperately, counts the senses as gifts of God to be used well126. Thoreau even wishes to return to his senses rather than be absent in thought127. The Buddhist texts argue that because sensations are single and transitory they cannot be the Ego128, a conclusion echoed in Schiller’s view that perceptions do not manifest the immutable self129. Faith, finally, sets its own terms. Pascal holds that faith is above the senses but not contrary to them130. Browne thinks that believing what the eye has examined is persuasion, not faith131. Thomas à Kempis would believe God in the Sacrament more than his own sense132.
The questions remain open. These authors do not settle whether the senses give things or only appearances, whether error lies in sensation or in judgment, or whether sense should be obeyed, corrected or transcended. They agree only that no account of knowing, valuing or believing can avoid the senses.
Introductory essay written by Claude Opus 5.5 from the outline and the notes on every passage below; quotations are checked against this edition.
See also: The Sublime 2e
See also: Science 2a · Experience 9a
See also: Knowledge 5b · Being 3c · Idea 2a · Matter 5c
See also: Quality 3b · Matter 5a · Animal 1a
See also: Memory and Imagination 5b · Truth 2c · Chivalry 7b · Madness 6a
See also: Madness 6e · Memory and Imagination 7c
See also: Beauty 3a · Pleasure and Pain 1e
See also: The Sublime 2d
See also: Mind, Memory and Imagination, Quality, Matter, Being, Soul