In the Republic, the Philosopher Kings are presented as first ascending towards intelligible reality before descending back into the realm of human affairs in order to govern. What form does this descent take in the analogous case of the rational soul? The main task of reason is to govern the body and the appetitive soul. However, because appetitive impulses are not directly responsive to the calculating power of reason, they are susceptible to the same sorts of perspectival illusions that we find in perception, with pleasures or pains that are nearer in time taking on disproportionate magnitude, thus leading us to indulge compulsively in short-term pleasure at the cost of long-term pain or to avoid short-term pain to maximize our long-term pleasure. This perspectival error cannot be corrected so long as we remain on the level of pleasure and pain themselves. Medicine, however, is able to look beyond sensations to the states of the body in which they are rooted, providing the rational soul with norms against which to measure the fittingness of desires. In this way, medicine serves as an intermediary art through which the rational soul imposes its rule on the body and appetitive soul.