Microcosm and Macrocosm

In the Philebus (28d–30d), Plato argued that human beings and the universe are both composed of an elemental body and a rational soul, and that just as the human body derives from the universe's body, the human soul must derive from the universe's soul. The universe is, therefore, not only an orderly system but an intelligent organism as well. Plato expounded this theme at greater length in the Timaeus (29d–47e), where he explained how the structure of the human being parallels that of the universe through certain correspondences in body and soul. Just as the body of the universe is spherical, and its soul is composed of orbits along which the planets wander, so too the soul of the human being is composed of orbits along which its emotions rove, and it inhabits the head, which is spherical. The rest of the human body exists merely to serve the head.

Unlike the macrocosm, which contains all things and is immortal, and hence has no need of sensory or digestive organs or limbs for locomotion, the microcosm is only a part of the whole, and its existence is threatened by the surrounding elements, so that it needs such additional parts to perceive and avoid danger and to replenish the nutrients it loses. Furthermore, the external disturbances that threaten the microcosm cause the orbits of its soul to be disrupted, throwing its emotions into disarray. Yet when the disordered microcosm observes the heavens, it sees there the orderly motions of the planets following the orbits of the macrocosmic soul. With the aid of philosophical study, it becomes aware of the correspondence between itself and its great counterpart. Having attained this insight, the microcosm realizes that just as the universe employs reason to govern the planets, it too should employ reason to govern its emotions. In this way the microcosm overcomes its inner discord and prepares its soul for a return to the heavens from which it came.