Blessed is he who preaches virtue by means of his deeds. But if you say something that pertains to virtue, but do the opposite, this will not save you.
We ought to learn the virtues through practicing them, not merely through talking about them, so that by acquiring the habit of them we do not forget what is of benefit to us. 'The kingdom of God,' St. Paul says, 'resides not in words but in power' (I Cor. 4:20). For he who tries to discover things through actual practice will come to understand what gain or loss lies in any activity that he pursues.
We must with unflagging zeal and care give ourselves to the pursuit of virtue, and constantly occupy ourselves in its practice, lest at any time progress may cease, and regress immediately take its place.... To cease to acquire means to lose, for the will which goes no longer forward will not be far from peril of falling back.
Brothers, as long as you have breath in your bodies, strive for your salvation. Before the hour comes in which we shall weep for ourselves, let us practice virtue eagerly. For I tell you that if you knew what good things are in heaven, what promise is laid up for the saints and how those who have fallen away from God are punished and also what torments are laid up for those who have been negligent – especially those who have known the truth and have not led a way of life worthy of it so as to inherit that blessedness which is reserved for the saints and to flee the punishments of these torments – then you would endure every pain in order to be made perfect in the virtue which is according to Christ.
Unless curbed by the fear of God that accompanies the practice of the virtues, spiritual knowledge leads to vanity; for it encourages the person puffed up by it to regard as his own what has merely been lent to him, and to use his borrowed intelligence to win praise for himself. But when his practice of the virtues increases concomitantly with his longing for God, and he does not arrogate to himself more spiritual knowledge than is needed for the task in hand, then he is made humble, reduced to himself by principles which are beyond his capacity.
But if you are fearful of becoming self-righteous from working for your own salvation, or afraid of being overcome by spiritual pride, examine yourself and observe that the person who is afraid of becoming self-righteous suffers from blindness. For he does not see how self-righteous he is.
Do not be surprised that when you draw near to virtue, grievous and intense tribulations come to you on all sides: for virtue is not considered virtue, if it does not involve hard work.
Just as one cannot buy education or artistic skills for any price without working at it, so one cannot attain the habit of exercising the virtues without zeal and diligence.
The virtues follow one from another in succession, so that the path of virtue does not become grievous and burdensome, and so that by being achieved in order progressively they may be made light; thus the hardships endured for virtue's sake should be cherished by a man as is the good itself.