De Ebrietate

Accordingly we must, on these accounts, remind the man who gives himself airs by reason of his power of deliberating, or of wisely choosing one kind of objects and avoiding others, that if the same unalterable perceptions of the same things always occurred to us, it might perhaps be requisite to admire the two faculties of judging which are implanted in us by nature, namely, the outward senses and the intellect, as unerring and incorruptible, and never to doubt or hesitate about anything, but trusting in every first appearance to choose one kind of thing and to reject the contrary kind.

But since we are found to be influenced in different manners by the same things at different times, we should have nothing positive to assert about anything, inasmuch as what appears has no settled or stationary existence, but is subject to various, and multiform, and ever-recurring changes. For it follows of necessity, since the imagination is unstable, that the judgment formed by it must be unstable likewise;

and there are many reasons for this. In the first place, the differences which exist in animals are not in one particular only, but are unspeakable in point of number, extending through every part, having reference both to their creation and to the way in which they are furnished with their different faculties, and to their way of being supported and their habits, and to the manner in which they choose and avoid different things, and to the energies and motions of the outward senses, and to the peculiar properties of the endless passions affecting both the soul and body.

For without mentioning those animals which have the faculty of judgment, consider also some of those which are the objects of judgment, such as the chameleon and the polypus; for they say that the former of these animals changes his complexion so as to resemble the soils over which he is accustomed to creep, and that the other is like the rocks of the sea-shore