Complex sentence: He felt that Aristotle merely refuted the idea of Plato who believed the various functions of the soul (understanding, opinion, desire, etc.) reflected diverse parts of the soul which were located in different organs.
Split into simpler sentences: He felt that Aristotle merely refuted the idea of Plato. The latter believed the various functions of the soul (understanding, opinion, desire, etc.) reflected diverse parts of the soul, which were located in different organs.