Athanasius of Alexandria

We need only to will perfection, since it is within our power and is developed by us, for, when the soul keeps the understanding in its natural state, perfection is confirmed. The soul is in its natural state when it remains as it was created, and it was created beautifully and exceedingly upright. For this reason, Joshua, the son of Nave [Nun], commanded the people: “Incline your hearts to the Lord the God of Israel,” and John: “Make straight his paths.” Rectitude of soul, then, consists in preserving the intellect in its natural state, as it was created. On the other hand, when the intellect turns aside and deviates from its natural state, the soul is said to be evil. Thus, the matter is not difficult; if we remain as we were made, we are in a state of virtue; but, if we think evil thoughts, we are accounted evil. If, then, perfection were a thing to be acquired from without, it would indeed be difficult; but, since it is within us, let us guard against evil thoughts and let us constantly keep our soul for the Lord, as a trust received from him, so that he may recognize his work as being the same as when he made it. LIFE OF ST.