Nicene and Post-Nicene Fathers, Vol. IV:
Writings in Connection with the Manichæan Controversy.: Chapter 6

Chapter 6.—Virtue Gives Perfection to the Soul; The Soul Obtains Virtue by Following God; Following God is the Happy Life.

9.  No one will question that virtue gives perfection to the soul.  But it is a very proper subject of inquiry whether this virtue can exist by itself or only in the soul.  Here again arises a profound discussion, needing lengthy treatment; but perhaps my summary will serve the purpose.  God will, I trust, assist me, so that, notwithstanding our feebleness, we may give instruction on these great matters briefly as well as intelligibly.  In either case, whether virtue can exist by itself without the soul, or can exist only in the soul, undoubtedly in the pursuit of virtue the soul follows after something, and this must be p. 44 either the soul itself, or virtue, or something else.  But if the soul follows after itself in the pursuit of virtue, it follows after a foolish thing; for before obtaining virtue it is foolish.  Now the height of a follower’s desire is to reach that which he follows after.  So the soul must either not wish to reach what it follows after, which is utterly absurd and unreasonable, or, in following after itself while foolish, it reaches the folly which it flees from.  But if it follows after virtue in the desire to reach it, how can it follow what does not exist? or how can it desire to reach what it already possesses?  Either, therefore, virtue exists beyond the soul, or if we are not allowed to give the name of virtue except to the habit and disposition of the wise soul, which can exist only in the soul, we must allow that the soul follows after something else in order that virtue may be produced in itself; for neither by following after nothing, nor by following after folly, can the soul, according to my reasoning, attain to wisdom.

10.  This something else then, by following after which the soul becomes possessed of virtue and wisdom, is either a wise man or God.  But we have said already that it must be something that we cannot lose against our will.  No one can think it necessary to ask whether a wise man, supposing we are content to follow after him, can be taken from us in spite of our unwillingness or our persistence.  God then remains, in following after whom we live well, and in reaching whom we live both well and happily.  If any deny God’s existence, why should I consider the method of dealing with them, when it is doubtful whether they ought to be dealt with at all?  At any rate, it would require a different starting-point, a different plan, a different investigation from what we are now engaged in.  I am now addressing those who do not deny the existence of God, and who, moreover, allow that human affairs are not disregarded by Him.  For there is no one, I suppose, who makes any profession of religion but will hold that divine Providence cares at least for our souls.