Which of the following is NOT a part of Plato's definition of the soul?

Plato's definition of the soul includes three key parts: reason, spirit, and appetite. Each of these aspects corresponds to different elements of human personality and behavior. Reason is the rational part that seeks truth and knowledge, spirit represents the emotional and spirited aspect that drives ambition and courage, and appetite encompasses desires for physical pleasures and basic needs.

Intuition, however, is not explicitly classified as a separate part of the soul in Plato's philosophy. While he does discuss various functions and capacities of the soul, intuition as a standalone concept does not fit into his tripartite model of the soul. Therefore, identifying intuition as the aspect that is NOT part of Plato's definition helps in understanding his philosophical framework regarding human nature and the functioning of the soul.