The theory of knowledge that Plato claims to demonstrate in the slave boy scene of The Meno is that we do not learn, but rather that learning is just a process of recollection, of remembering what we have forgotten. He says that we learned everything in an earlier life, before we became people. So, we already have all of our knowledge. He demonstrates this theory by asking the slave boy various geometry questions which the slave boy answers correctly (even though they are pretty much just "yes or no questions)- proving that he knows and understands geometry, although he has not learned it previously. Therefore the knowledge was "recollected. As Socrates says in the text, "And if there have been always true thoughts in him, both at the time when he was and was not a man, which only need to be awakened into knowledge by putting questions to him, his soul must have always possessed this knowledge, for he always either was or was not a man? (Plato, p.55). This quote explains
Plato's view on already having knowledge, of just having to "awaken it.
From The Republic, his theory of knowledge is put in an analogy with people who lived in caves for most of their lives and then came out into the real "outside world which had a totally different reality than what they were used to. When they entered this new world, it is extremely difficult for them to adjust to all of its different aspects, for example the difference in light (their eyes cannot adjust to the change in brightness). Living in a cave their whole lives, they were used to seeing just darkness and shadows on walls. Then when they went out into the outer world there was sunlight, so naturally they could not learn to live in the new environment. So to put this analogy together with knowledge, "...certain professors of education must be wrong when they say that they can put a knowledge into the soul which was not there before, like sight into blind eyes (Plato