Human behavior, says Plato, flows from three main sources: desire, emotion, and knowledge. Desire, appetite, impulse, instinct—these are one; emotion, spirit, ambition, courage—these are one; knowledge, thought, intellect, reason—these are one. Desire has its seat in the loins; it is a bursting reservoir of energy, fundamentally sexual. Emotion has its seat in the heart, in the flow and force of the blood; it is the organic resonance of experience and desire. Knowledge has its seat in the head; it is the eye of desire, and can become the pilot of the soul.
