Phaedo.And on seeing a picture of Simmias he can be reminded of Simmias himself?Yes, said he.All these examples show, then, that recollection is caused by like things and also by unlike things, do they not?Yes.And when one has a recollection of anything caused by like things, will he not also inevitably consider whether this recollection offers a perfect likeness of the thing recollected, or not?Inevitably, he replied.Now see, said he, if this is true. We say there is such a thing as equality. I do not mean one piece of wood equal to another, or one stone to another, or anything of that sort, but something beyond that—equality in the abstract. Shall we say there is such a thing, or not? We shall say that there is, said Simmias, most decidedly.And do we know what it is?Certainly, said he.Whence did we derive the knowledge of it? Is it not from the things we were just speaking of? Did we not, by seeing equal pieces of wood or stones or other things, derive from them a knowledge of abstract equality, which is another thing? Or do you not think it is another thing? Look at the matter in this way. Do not equal stones and pieces of wood, though they remain the same, sometimes appear to us equal in one respect and unequal in another?Certainly.Well, then, did absolute equals ever appear to you unequal or equality inequality?No, Socrates, never.Then, said he, those equals are not the same as equality in the abstract.Not at all, I should say, Socrates.But from those equals, said he, which are not the same as abstract equality, you have nevertheless conceived and acquired knowledge of it?Very true, he replied.And it is either like them or unlike them?Certainly.It makes no difference, said he. Whenever the sight of one thing brings you a perception of another, whether they be like or unlike, that must necessarily be recollection.Surely.Now then, said he, do the equal pieces of wood and the equal things of which we were speaking just now affect us in this way: Do they seem to us to be equal as abstract equality is equal, or do they somehow fall short of being like abstract equality?They fall very far short of it, said he.Do we agree, then, that when anyone on seeing a thing thinks, This thing that I see aims at being like some other thing that exists, but falls short and is unable to be like that thing, but is inferior to it, he who thinks thus must of necessity have previous knowledge of the thing which he says the other resembles but falls short of? We must.Well then, is this just what happened to us with regard to the equal things and equality in the abstract?It certainly is.