# On the Vital Principle/Book 2/Chapter 6

Let us, before proceeding further, speak upon the objects of perception in relation to each of the senses. The object of perception is spoken of in a three-fold manner, as there are two ways in which we speak of perceiving objects distinctly, and one in which we speak of perceiving them accidentally; and of those two ways one signifies the property which is peculiar to each sense, and the other the property which is common to all the senses. I mean by peculiar property that which cannot be perceived by any other than its own sense, and concerning which that sense cannot be deceived—as colour for sight, sound for hearing, and savour for taste. The touch, indeed, discriminates several differences of quality, but every other sense distinguishes only its own subjects; and thus sight or hearing is never deceived as to whether it is colour or sound which is seen or heard, although it may be deceived as to what or where the coloured, what or where the sonorous body may be.
Such then the properties which are said to be peculiar and to belong to particular senses; but there ​are properties, such as motion, rest, number, form and magnitude, which are termed common, as they belong not to any one sense, but to all in common. Thus, there is a movement which is perceptible both by Touch and Sight. An object is said to be perceived accidentally when, for example, something white may be the Son of Diares—for the percipient is sensible of the individual accidentally, because of his being an accident of that which is perceived; and, therefore, no impression is made by that which is perceived, as a special object, upon the percipient.
The properties of bodies, which are in themselves perceptible, are, strictly speaking, peculiar properties; and to such each particular sense is naturally and essentially related.

## Notes

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​Note 1, p. 90. The Touch indeed, &c.] This sense has a wider range of perception than any other that is, it is not restricted, like the Sight, Hearing, and Smell, to a definite organism and one mode of impression; and, besides being extended over the body, it is essential to animal existence. The text makes no allusion to the Taste, because this sense was regarded as subsidiary to or a modification of the Touch. The special senses are Sight, Hearing, and Smell; Taste is less definite, as the tongue is sensible ​of tangible as well as sapid qualities; and Touch is extended over the body. Some properties, however, which are enumerated, are subject to all the senses, and, hence, termed common; but the attempted illustration of them by "a kind of motion" (κίνησις τις) does not, owing to its vagueness, assist in explaining them.
Note 2, p. 91. An object is said to be perceived, &c.] An example in illustration of casual or accidental perception; but it is by its wording so obscure as to stand itself in need of elucidation. The purport, however, seems to be, that the percipient does not, by sight, (as sight distinguishes only colour and form) discern what the white object really is; but the other senses, by some accidental perception, coming in aid of the special sense, may determine that the white object is a certain individual. There may besides, perhaps, be a covert allusion to the two-fold acceptation of the term accident, which signified then as it does now both casual incidents and the real, or inalienable properties of bodies; and if so, the passage may imply that the individual is perceived by chance; detected, that is, by a mere guess. It is of little moment, but the individual alluded to is said, by Philoponus, to have been a friend of Aristotle's; and that letters which had passed between them were extant in his time.
* ↑ De Sensu et Sens. iv. 2.