Carneades asserts that there are two kinds of appearances; and that the first kind may be divided into those which can be perceived and those which cannot; and the other into those which are probable and those which are not. Therefore, those which are pronounced to be contrary to the senses and contrary to evidentness belong to the former division; but that nothing can be objected to those of the second kind. Wherefore his opinion is, that there is no appearance of such a character that perception will follow it, but many such as to draw after them probability. Indeed, it would be contrary to nature if nothing were probable; and that entire overturning of life, which you were speaking of, Lucullus, would ensue. Therefore there are many things which may be proved by the senses; only one must recollect that there is not in them anything of such a character that there may not also be something which is false, but which in no respect differs from it in appearance; and so, whatever happens which is probable in appearance, if nothing offers itself which is contrary to that probability, the wise man will use it; and in this way the whole course of life will be regulated. And, in truth, that wise man whom you are bringing on the stage, is often guided by what is probable, not being comprehended, nor perceived, nor assented to, but only likely; and unless a man acts on such circumstances there is an end to the whole system of life. For what must happen? Has the wise man, when he embarks on board ship, a positive comprehension and perception in his mind that he will have a successful voyage? How can he? But suppose he goes from this place to Puteoli, thirty furlongs, in a seaworthy vessel, with a good pilot, and in fine weather like this, it appears probable that he will arrive there safe. According to appearances of this kind, then, he will make up his mind to act or not to act; and he will be more willing to find the snow white than Anaxagoras, who not only denied that fact, but who affirmed, because he knew that water, from which snow was congealed, was of a dark colour, that snow did not even look white. And he will be influenced by anything which affects him in such a way that the appearance is probable, and not interfered with by any obstacle. For such a man is not cut out of stone or hewn out of oak. He has a body, he has a mind, he is influenced by intellect, he is influenced by his senses, so that many things appear to him to be true, and yet not to have conspicuous and peculiar characteristics by which to be perceived. And therefore the wise man does not assent to them, because it is possible that something false may exist of the same kind as this true thing. Nor do we speak against the senses differently from the Stoics, who say that many things are false, and are very different from the appearance which they present to the senses.