In the conversation, Socrates talks about the true forms of things. The idea is that there is such a thing as a true bed, or a true chair, or true virtue, or whatever else. So when an artisan builds a chair, he is building the idea of a chair and not the true chair which exists in the mind of God. God is the only one who can know things in their true forms apparently...which is disturbing. Socrates really goes out of his way to prove a point that he cannot prove. I will explain.
             If Homer was in no position to teach about X, and someone learns from Homer, Socrates is saying that said person can have no true knowledge of the subject either and it is just an imitation. If X stands for virtue or patriotism for instance, then the follower can know no more than the master. But I don't find this to be true simply because it is possible that perhaps someone who studies Homer initially knew more about virtue than Homer himself did, or somehow the student has gained more knowledge along the way.
             To do a reduction ad absurdum of his argument, I will use the example of music. If what Socrates is saying is true, then no one who studied Homer will ever surpass him and no one who studies under them would surpass them and you would find that the art becomes watered down and gradually gets worse. But let's say someone copied the original musician banging on a rock with a stick (but we must note that the original musician was an imitator if there were any birds around and therefore produced a perverted form of the art), well, if what Socrates is saying is true then we would never have Mozart or the Beatles, instead, we would have less music than the original man started with, because he himself was an imitator.
             The idea that a person may not know of many things is a hard pill to swallow. Glaucon swallows it pretty easily, along with anything else Socrates happens to say. And so I must reject his ideas of form and imitation because whi...