“Indeed,” said Cebes, “I am not at all so disposed; however, I by no means say that there are not many things that disturb me.”

“Then,” he continued, “we have quite agreed to this, that a contrary can never be contrary to itself.”

“Most certainly,” he replied.

“But, further,” he said, “consider whether you will agree with me in this also.  Do you call heat and cold any thing?”

“I do.”

“The same as snow and fire?”

“By Jupiter!  I do not.”

“But heat is something different from fire, and cold something different from snow?”

“Yes.”

“But this, I think, is apparent to you—­that snow, while it is snow, can never, when it has admitted heat, as we said before, continue to be what it was, snow and hot; but, on the approach of heat, it must either withdraw or perish?”

“Certainly.”

“And, again, that fire, when cold approaches it, must either depart or perish; but that it will never endure, when it has admitted coldness, to continue what it was, fire and cold?”

121.  “You speak truly,” he said.

“It happens, then,” he continued, “with respect to some of such things, that not only is the idea itself always thought worthy of the same appellation, but likewise something else which is not, indeed, that idea itself, but constantly retains its form so long as it exists.  What I mean will perhaps be clearer in the following examples:  the odd in number must always possess the name by which we now call it, must it not?”

“Certainly.”

“Must it alone, of all things—­for this I ask—­or is there any thing else which is not the same as the odd, but yet which we must always call odd, together with its own name, because it is so constituted by nature that it can never be without the odd?  But this, I say, is the case with the number three, and many others.  For consider with respect to the number three:  does it not appear to you that it must always be called by its own name, as well as by that of the odd, which is not the same as the number three?  Yet such is the nature of the number three, five, and the entire half of number, that though they are not the same as the odd, yet each of them is always odd.  And, again, two and four, and the whole other series of number, though not the same as the even, are nevertheless each of them always even:  do you admit this, or not?”

122.  “How should I not?” he replied.

“Observe then,” said he, “what I wish to prove.  It is this—­that it appears not only that these contraries do not admit each other, but that even such things as are not contrary to each other, and yet always possess contraries, do not appear to admit that idea which is contrary to the idea that exists in themselves, but, when it approaches, perish or depart.  Shall we not allow that the number three would first perish, and suffer any thing whatever, rather than endure, while it is still three, to become even?”