Plato believed that the soul is divided into three parts: rational, spirited, and appetitive. The rational part seeks wisdom and understanding, the spirited part deals with emotions and self-control, and the appetitive part is responsible for desires and instincts.

No - there was three centres according to Plato:

Nous (Psyche) - the highest part - reason, wisdom and insight.

Thymos - the middle level - passion, fight and drive: arising from the throat, hear and stomach.

Epithymia - the bottom level - desire and instinct: basic survival needs and appetites.

So the stomach is just one sub-part of the thre major parts.

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