The course of the argument in Plato s Republic is primarily organized around a single formal engine, the city-soul analogy. To better understand its procedure and the use that Plato might have expected from it, we will seek to understand, in this dissertation, the meanings of proportion and elements employed therein by making more explicit the comparison that Plato himself makes through Socrates: the one between the order of letters in words and the sets of parts that make up units (either in the case of individuals or cities). From this understanding we can address more throughly the tripartions of the city and the soul the dialogue suggests, the theory of desire contained therein and the possible harmonization of our conflicting motivations, which lead to a collective concept of happiness.