Enneads IV.7: Of the Immortality of the Soul: Polemic Against Materialism
The Body Cannot Possess Virtue
Neither do beauty or justice possess extension, I suppose; and their conception must be similar. These things can be cognized or retained only by the indivisible part of the soul. If the latter were corporeal, where indeed could virtues, prudence, justice and courage exist? In this case, virtues (as Critias thought), would be no more than a certain disposition of the spirit, or blood (as Empedocles also thought). For instance, courage and temperance would respectively be no more than a certain irritability, and a fortunate temperament of the spirit; beauty would consist in the agreeable shape of outlines, which cause persons, in whom they occur, to be called elegant and handsome. Under this hypothesis, indeed, the types of spirit might possess vigor and beauty. But what need would it have of temperance? On the contrary, the spirit would seek to be agreeably affected by the things it touches and embraces, to enjoy a moderate heat, a gentle coolness, and to be in contact only with sweet, tender, and smooth entities. What incentive would the spirit have to apportion rewards to those who had deserved them?
Are the notions of virtue, and other intelligible entities by the soul thought eternal, or does virtue arise and perish? If so, by what being, and how will it be formed? It is the same problem that remains to be solved. Intelligible entities must therefore be eternal and immutable, like geometrical notions, and consequently cannot be corporeal. Further, the subject in whom they exist must be of a nature similar to theirs, and therefore not be corporeal; for the nature of body is not to remain immutable, but to be in a perpetual flow.