The culmination of the philosophical quest for understanding is knowledge of the world of forms. In a kind of intuitive knowledge the philosopher, who has left behind the world of murky objects and shadowy realities of this world, understands the highest world of ideas in a flash. For the philosopher it is the only knowledge deserving of the name.

If there is a faculty of reason that represents the highest kind of understanding, there must be some corresponding level of reality that is universal and unchanging. The forms are changeless, eternal, and nonmaterial essences, such as eternal patterns of beauty or justice. By comparison, the beautiful objects and just actions you see in your daily life are just copies of the forms. Objects in experience may become beautiful and then cease to be beautiful, but beauty itself has a separate existence from the changing things of this world. Plato maintains that the actual objects of the visible world are only copies of, or “partake” of, the world of forms. Thus every act of goodness, or every triangle you see, is but a copy of the form of the Triangle.

You have already seen the influence of Socrates and Pythagoras on Plato. With the forms you see how the influence of Heraclitus comes into play. In Plato's view, the world of our senses was a world of “becoming;” only the realm of forms was one of complete being. Plato thought that if Heraclitus was right in maintaining that all reality was in flux, then the only faculty appropriate to knowing the world would be opinion. Therefore, there must be an unchanging world that is known.

According to Plato, our souls were acquainted with the forms before being united with our bodies. Our minds discover the forms in at least three different ways. First there is recollection. Before our souls were united with our bodies, the soul was acquainted with the Forms. People thus recollect what their souls knew in a prior state of existence. Visible things remind them of essences previously known. Education is actually a process of reminiscence. Second, people arrive at the knowledge of forms through the activity of dialectic, which is the process of abstracting objects and discovering the relations of all divisions of knowledge to each other. And third there is the power of desire, or love (eros) which leads people step by step, as Plato described in the Symposium, from the beautiful object to the beautiful thought and then to the very essence of Beauty itself.

The theory is metaphysical, but it explains more than that. When people talk about beauty or goodness, they are not talking only about this or that beautiful object or some good action. For to raise the question of whether a philanthropist's generous action is good we first need to (in Socratic fashion) solve a more general question about what goodness is. Knowledge involves more than seeing. It involves understanding.