Plato's argument of the divisibility of the soul from his dioloque, "The Republic".

Plato's Divisibility of the Soul A soul is not a simple entity. The soul has structure and divides into three parts. Plato is the first to give the soul this complexity and does so in his dialoque, Republic. According to Plato, the soul possesses reason, spirit, and appetite. Plato proves that the soul has three parts so that the virtues he's applied to the city will apply to individuals. In this essay, I will first …

…together. It is necessary for these separate parts to operate together right so that the soul/city will work how it is supposed to work. The soul is comparable to a city. Both the soul and Plato's city have reason/wisdom, spirit/courage, and appetite/moderation. The virtues Plato give his city, which create the three classes, make his city comparable to an individual because individuals have souls that divide into three parts as well.