Phaedo

by Plato

Say so, yes, replied Simmias, and swear to it, with all the confidence in life.

And do we know the nature of this absolute essence?

To be sure, he said.

And whence did we obtain our knowledge? Did we not see equalities of material things, such as pieces of wood and stones, and gather from them the idea of an equality which is different from them? For you will acknowledge that there is a difference. Or look at the matter in another way:—Do not the same pieces of wood or stone appear at one time equal, and at another time unequal?

That is certain.

But are real equals ever unequal? or is the idea of equality the same as of inequality?

Impossible, Socrates.

Then these (so-called) equals are not the same with the idea of equality?

I should say, clearly not, Socrates.

And yet from these equals, although differing from the idea of equality, you conceived and attained that idea?