Book 4
11
The first then and highest purity is that which is in the soul; and we say the same of impurity. Now you could not discover the impurity of the soul as you could discover that of the body: but as to the soul, what else could you find in it than that which makes it filthy in respect to the acts which are her own? Now the acts of the soul are movement towards an object or movement from it, desire, aversion, preparation, design (purpose), assent. What then is it which in these acts makes the soul filthy and impure? Nothing else than her own bad judgments (κρίματα). Consequently the impurity of the soul is the soul’s bad opinions; and the purification of the soul is the planting in it of proper opinions; and the soul is pure which has proper opinions, for the soul alone in her own acts is free from perturbation and pollution.
