Discuss the main subject of Plato`s Republic.
The main subject of the Republic is the nature of the soul. This is clearly set out in the first book, and yet the majority of the text is devoted to the organization of the ideal city. There are two possible reasons for this apparent dichotomy between the putative and actual subject matter. The first, explicitly stated by the Socratic character, is that the soul per se is difficult to investigate, but that the city, being the soul writ large, can be studied in order to discover things about the soul that would not be apparent in direct study of the soul itself. The second possible reason is that the condition of the soul is affected by the polis, and thus that to understand (and ideally improve) the soul, one must understand and regulate the polis.
The tripartite model of the soul, with rational, willful, and emotional parts is paralled in the three class of citizen in the polis.