"In Meno, Plato's character (and old teacher) Socrates is challenged by Meno with what has become known as the sophistic paradox, or the paradox of knowledge:
Meno: And how are you going to search for [the nature of virtue] when you don't know at all what it is, Socrates? Which of all the things you don't know will you set up as target for your search? And even if you actually come across it, how will you know that it is that thing which you don't know?In other words, if you don't know any of the attributes, properties, and/or other descriptive markers of any kind that help signify what something is (physical or otherwise), you won't recognize it, even if you actually come across it. And, as consequence, if the converse is true, and you do know the attributes, properties and/or other descriptive markers of this thing, then you shouldn't need to seek it out at all. The result of this line of thinking is that, in either instance, there is no point trying to gain that "something"; in the case of Plato's aforementioned work, there is no point in seeking knowledge.
Socrates' response is to develop his theory of anamnesis. He suggests that the soul is immortal, and repeatedly incarnated; knowledge is actually in the soul from eternity (86b), but each time the soul is incarnated its knowledge is forgotten in the shock of birth. What one perceives to be learning, then, is actually the recovery of what one has forgotten. (Once it has been brought back it is true belief, to be turned into genuine knowledge by understanding.) And thus Socrates (and Plato) sees himself, not as a teacher, but as a midwife, aiding with the birth of knowledge that was already there in the student.
The theory is illustrated by Socrates asking a slave boy questions about geometry. At first the boy gives the wrong answer; when this is pointed out to him, he is puzzled, but by asking questions Socrates is able to help him to reach the true answer. This is intended to show that, as the boy wasn't told the answer, he could only have reached the truth by recollecting what he had already known but forgotten."
All this is highly suspicious to me. Unless we think of "the soul" as the constraints of an embodied existence in a permanent world whose rules transcend our existence.