The Lord ordereth 'all things in measure and weight,' and brings on us the temptations which do not exceed our power to endure them, but tests all that fight in the cause of true religion by affliction, not suffering them to be tempted above that they are able to bear.
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.
Temptations are sent for improvement when God delivers his righteous ones to various temptations, humiliating them for some slight and unimportant offense, or to increase their purity, in order that every uncleanliness of thought, or... dross which He sees they have harbored in secret, may be burnt away in this present life, and that so He may bring them, as it were pure gold, to the future judgment...
Remember that a good action is always either preceded or followed by temptations. God permits this so that the virtue, exercised in that particular action, may be confirmed, consolidated, steeled.
One should nourish the soul with the word of God: for the word of God, as St. Gregory the Theologian says, is angelic bread, by which are nourished souls who hunger for God. Most of all, one should occupy oneself with reading the New Testament and the Psalter, which one should do standing up. From this there occurs an enlightenment in the mind, which is in the mind, which is changed by a Divine change.
Do not approach the words of the mysteries contained in the divine Scriptures without prayer and beseeching God for help, but say: 'Lord, grant me to perceive the power in them!' Reckon prayer to be the key to the true understanding of the divine Scriptures.
The person who truly comes to serve God must prepare his soul, as it says in the Wisdom of Sirach (2:1), for temptations. Thus, that he will never be surprised or disturbed by what happens, believing that nothing happens without the providence of God and where there is the providence of God certainly what happens is good and for the benefit of the soul. For, everything that God does, He does for our benefit and because He loves us and has pity on us. We must, as the Apostle says, 'In everything give thanks' (1 Thess. 5:18), for His goodness.
A human being who does not endure courageously the unpleasant burdens of temptations, will never produce fruit worthy of the divine wine-press and eternal harvest, not even if one possesses all other virtues. For one is only perfected through zealously enduring both all the voluntary and involuntary afflictions.
You can see that a city is prosperous by the wealth of goods for sale in the market. Land too we call prosperous if it bears rich fruit. And so also the soul may be counted prosperous if it is full of good works of every kind. But first of all it has to be farmed energetically. Then it must be watered by abundant streams of heavenly grace for it to bring forth fruit, some thirty fold, some sixty fold, and some a hundred fold. The soul only acquires goodness and the capacity of fulfilling its duties if it has the grace of God On the other hand, what is uglier or more disgusting than a soul given over to base passions? Look at the hot-headed person: he is like a wild beast. Consider the slave of lust or gluttony: who can bear the sight of him? Pity the victim of melancholy whose spirit is totally prostrated. It is for us to seek to acquire beauty so that the Bridegroom, the Lord, may welcome us into his presence and say, “You are utterly fair, my love, and there is no flaw in you.” (Song of Sol 4:7)
Put aside bodily considerations when you stand in prayer, lest the bite of a flea, a gnat or a fly deprive you of the greatest gain afforded by prayer.
What is the source from which man's will can draw suitable principles of guidance? For a non-believer, an answer to this is extremely difficult and essentially impossible. Are they to be drawn from science? In the first place, science is interested primarily in questions of knowledge and not morals, and secondly, it does not contain anything solid and constant in principles because it is constantly changing. From philosophy? Philosophy teaches about the relativity of its truths and does not claim their unconditional authority. From practical life? Even less. This life itself is in need of positive principles which can remove from it unruly and unprincipled conditions. But while the answer to the present question is so difficult for non-believers, for a believing Christian the answer is simple and clear. The source of good principles is God's will, and this is revealed to us in the Savior's teaching, in His Holy Gospel. It alone has an unconditional, steadfast authority in this regard; and it alone teaches us self-sacrifice and Christian freedom, Christian equality and brotherhood (a concept stolen by those outside the Faith). The Lord Himself said of true Christians, 'Not everyone who says to Me, Lord, Lord, will enter the kingdom of heaven, but he who does the will of My Father' (Matt. 7:21).