ternal realities, in contrast to the shifting, imperfect, material phenomena of the senses" (Grant 217). This point is clarified in the dialogue Phaedo, in which Socrates argues with Cebes over the nature of the soul. Using the dialectic, or question-and-answer method, Socrates indicates that the true reality of Ideas is invisible to the senses. In addition, Socrates argues that the Ideas which form "absolute reality" remain "always constant and invariable" (Plato 61). By contrast, the things of the material world are clearly visible to the senses and are constantly undergoing change. Thus, in this way, Socrates claims that there are "two classes of things, one visible and the other invisible," with "the visible being invariable, and the visible never being the same" (62). Socrates then goes on to indicate that the body is part of the visible world, whereas the soul is part of the invisible world. Therefore, the theory of Ideas holds that material objects are ideas are two "differing degrees of reality," with the world of Ideas being "more real" than the world of the senses (Nozick 138).
It has been noted that an Idea represents a "timeless essence or universal--a dynamic archetype of existents" (Long 152). This shows that the Platonic Ideas are models, or archetypes, for the things which make up the material world. According to Plato's theory, the things of the material world are reflections or imitations of Ideas. Normally, material things are perceived as being real. However, Plato contends that it is the Ideas which are real, with material things being mere imitations of them. Every object or concept which is perceived in the material world has a corresponding Idea. Somehow, the soul or mind causes each Idea to be manifested in the material world. Using the perception of a circle as an example, it can be said that "no real or genuine circle is presented to our senses; the real circle is the Idea of the circle, that...