Toward the end of Book VI and into Book VII of the Republic, Plato gives a series of metaphors for the role "the good itself" plays in our knowledge and values. We read here starting at line 507b of the G.M.A. Grube/C.D.C Reeve translation, where we hear that the form of the good is to our ability to know anything as the sun is to our ability to see anything. We conclude by discussing the first half of Plato's "divided line" image, whose lower half marks off reflections/images and then the material objects that these are images of. Because these are in the lower half, we can't have any real knowledge of them; thus physical science should be impossible. Follow along with us. Learn more about your ad choices. Visit megaphone.fm/adchoices