I have been well-disposed toward Oprah ever since she picked Anna Karenina as her summer reading choice a few years ago. Of course, the question is why she should have been able to get so many people to run out and buy a copy of Tolstoy's great novel, and - presumably - read it. I suspect that the late Plato would find the Oprah phenomenon not at all mysterious. Today's world has become an embodiment of the Myth of the Cave in Book 7 of The Republic: A great many people nowadays - perhaps most people - are preoccupied exclusively with images rather than realities. It is not Oprah who influences them. It an image on a screen identified as Oprah that does. The Julia Roberts admired by fans is not the real Julia Roberts, but an image of Julia Roberts carefully prepared for presentation on a large silver screen or a small glossy magazine cover. Socrates, as depicted by Plato, had the single goal of encouraging people not merely to think, but more precisely to think - and observe - for themselves. Thanks to their willing exposure to radio, television and films, people today are even less likely to do that than they were in Plato's day. For many these days, an idea - especially one that runs counter to so-called conventional wisdom - is hard to differentiate from a headache.