Rationalistic elements can also be found in Plato. To do so, in general, consider the views of Greek thinkers, and then further analyze its philosophy. In Plato's concept is an attempt to use similarities and differences of concepts "being" and "substance". Plato sees the concept of failure to resolve the issues that inevitably confront a philosopher. First of all, "being" does not help to understand how the possible true knowledge: "... it turns out that if there is a fixed, no one anywhere nothing could comprehend." To avoid harmful for human inference, Plato makes the quality of life and motionless realm of ideas, and "other." In this case, it brings being with the substance as the original. Substance begins to act realm of ideas and matter as an opportunity otherwise (Voegelin, 2006). They generate the visible world, to the knowledge they seek the mind of man. "Clear" is being extended farther and farther from the eyes of man, it becomes unintelligible to him (Robert, 2004). The idea of substance as the first principles associated with the idea of attitude of involvement solves another problem: a person opens the way to the knowledge of the world in its unity and diversity. In Plato's doctrine of being (ontology) can be constructed so as to justify and make clear the existence of correspondence between the articulation of language units (words, sentences, etc.) and "units" of the ontology (the entities that make up the world). In Plato distinguished the primary ontological units that meet certain language expressions. For example, Plato's primary element of the ontological structure is the idea. The world of unchanging ideas precedes and defines the world of changeable things. But the idea is not just the primary elements of existence, the primary being-certainty, is being, corresponding to an abstract ...