The first duty of a Christian, of a disciple and follower of Jesus Christ, is to deny oneself. To deny oneself means to give up one's bad habits, to root out of the heart all that ties us to the world; not to cherish bad desires and thoughts; to quench and suppress bad thoughts; to avoid occasions of sin; not to do or desire anything from self-love but to do everything out of love for God. To deny oneself means, according to the Apostle Paul, to be dead to sin and the world, but alive to God.
A truly intelligent man has only one care -- wholeheartedly to obey Almighty God and to please Him. The one and only thing he teaches his soul is how best to do things agreeable to God, thanking Him for His merciful Providence in whatever may happen in his life. For just as it would be unseemly not to thank physicians for curing our body, even when they give us bitter and unpleasant remedies, so too would it be to remain ungrateful to God for things that appear to us painful, failing to understand that everything happens through His Providence for our good. In this understanding and this faith in God lie salvation and peace of soul.
It is impossible for the mind to escape disturbing thoughts, but it is possible, for any who take sufficient care, either to admit them or reject them.
Learn to desire humility, for that will cover all your sins. All sin is hateful to God, but the most hateful of all is pride of heart. Do not consider yourself learned or wise, or all your toil will be lost and your ship will arrive empty at the shore.
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.
The belly when filled with all kinds of food gives birth to seeds of wantonness, nor can the mind, when choked with the weight of food, keep the guidance and government of the thoughts. For not only is drunkenness with wine wont to intoxicate the mind, but excess of all kinds of food makes it weak and uncertain, and robs it of all its power of pure and clear contemplation. The cause of the overthrow and wantonness of Sodom was not drunkenness through wine, but fullness of bread. Hear the Lord rebuking Jerusalem through the prophet. 'For how did thy sister Sodom sin, except in that she ate her bread in fullness and abundance?' (Ezek. xvi. 49)
If we remember the thief who, for a single confession on the cross, was taken into Paradise, we shall realize that it was not for the merit of the life he lived that he obtained so great blessedness, but that it was his by the gift of God, Who had mercy on him. Or, let us think of David, the king, whose two grievous and awful crimes were wiped away by one word of penitence. Neither here do we see that the merit of what he did was equal to obtaining pardon for such great offense, but the grace of God did the more abound when on the occasion of true penitence He did away with all that weight of sin for one single word of genuine confession. Again, when we consider the beginnings of man's calling and salvation, which, as the Apostle tells us, is not of ourselves or of our words, but we are saved by the gift and grace of God, we shall be able clearly to perceive how the end of perfection is not 'of him that willeth, nor of him that runneth, but of God Who showeth mercy,' Who makes us victors over our vices, although we have no merit at all of life or labors to weigh against them, nor does the effort of our will avail for us to reach the steep summit of righteousness, or to subdue the flesh which we are bound to use... For the outcome of all good flows from His grace, Who hath bestowed so great an eternity of bliss and such immeasurable glory, with manifold generosity, upon the weak will and the short life-work of man.
