Discoveries
OF THE
ANCIENTS AND MODERNS.
No. IV.
Of Sensible Qualities.
The most eminent philosophers of antiquity, Democritus, Socrates, Aristippus the chief of the Cyrenaïc sect, Plato, Epicurus, and Lucretius, affirmed, that cold and heat, odours and colours, were no other than sensations excited in our minds, by the different operations of the bodies surrounding us, and acting on our senses; even Aristotle himself was of opinion, that “sensible qualities exist in the mind.” Yet when Descartes, and after him Mallebranche, taught the very same truths, they were ascribed to these moderns, owing to the outcry they made, as if the opposite error, which they attacked in the schoolmen, had been that of all ages; and nobody deigned to search whether, in reality, it was so or not. Were we to bring into review all that the ancients have taught on this subject, we should be surprised at the clearness with which they have explained themselves, and at a loss to account how opinions came to be taken for new, which had been illustrated in their writings with such force and precision.
Democritus was the first who disarrayed body of its sensible qualities. He affirmed, that “the first elements of things having in them naturally neither whiteness nor blackness, sweetness nor bitterness, heat nor cold, nor any other quality, it thence follows, that colour, for example, exists only in our imagination or perception of it; as also, that bitterness and sweetness, which exist only in being perceived, are the consequences of the different manner in which we ourselves are affected by the bodies surrounding us, there being nothing in its own nature yellow or white, or red, sweet or bitter.” He indicates what kind of atoms produce such and such sensations: round atoms, for example, the taste of sweetness; pointed and crooked, that of tartness; bodies composed of angular and coarse parts, introducing themselves with difficulty into the pores, cause the disagreeable sensations of bitterness and acidity, &c. The Newtonians imitate this reasoning everywhere, in explaining the different natures of bodies.
Sextus Empiricus, explaining the doctrine of Democritus, says, “that sensible qualities, according to that philosopher, have nothing of reality but in the opinion of those who are differently affected by them, according to the different dispositions of their organs; and that from this difference of disposition arise the perceptions of sweet and bitter, heat and cold; and also, that we do not deceive ourselves in affirming that we feel such impressions, but in concluding that exterior objects must have in them something analogous to our feelings.”
Protagoras, the disciple of Democritus, carried farther than ever Democritus did the consequences of his system; for admitting with his master the perpetual mutability of matter which occasioned a constant change in things, he thence concluded, that whatever we see, apprehend, or touch, is just as they appear; and that the only true rule or criterion of things, was in the perception men had of them. From Protagoras, bishop Berkeley seems to have derived his idea, “that there is nothing in external objects but what the sensible qualities existing in our minds induce us to imagine, and of course that they have no other manner of existence; there being no other substratum for them, than the minds by which they are perceived, not as modes or qualities belonging to themselves, but as objects of perception to whatever is percipient.”
We should think we were listening to the two modern philosophers, Descartes and Mallebranche, when we hear Aristippus, the disciple of Socrates, exhorting men “to be upon their guard with respect to the reports of sense, because it does not always yield just information; for we do not perceive exterior objects as they are in themselves, but only as they affect us. We know not of what colour or smell they may be, these being only affections in ourselves. It is not the objects themselves that we are enabled to comprehend, but are confined to judge of them only by the impressions they make upon us; and the wrong judgments we form of them in this respect is the cause of all our errors. Hence, when we perceive a tower which appears round, or an oar which seems crooked in the water, we may say that our senses intimate so and so, but ought not to affirm that the distant tower is really round, or the oar in the water crooked: it is enough, in such a case, to say with Aristippus and the Cyrenaïc sect, that we receive the impression of roundness from the tower, and of crookedness from the oar; but it is neither necessary nor properly in our power to affirm, that the tower is really round, or the oar broken; for a square tower may appear round at a distance, and a straight stick always seems crooked in the water.”[312]
Everybody talks of whiteness and sweetness, but they have no common faculty to which they can with certainty refer impressions of this kind. Every one judges by his own apprehensions, and nobody can affirm that the sensation which he feels when he sees a white object, is the same with what his neighbour experiences in regard to the same object. He who has large eyes will see objects in a different magnitude from him whose eyes are little, and he who hath blue eyes, discern them under different colours from him who hath grey; whence it comes, that we give common names to things, of which, however, we judge very variously.
Epicurus, admitting the principles of Democritus, thence deduces “that colour, cold, heat, and other sensible qualities are not inherent in the atoms, but the result of their assemblage; and that the difference between them flows from the diversity of their size, figure, and arrangement; insomuch, that any number of atoms in one disposition creates one sort of sensation; and in another, another: but their own primary nature remains always the same.”