Do not be always wanting everything to turn out as you think it should, but rather as God pleases; then you will be undisturbed and thankful in your prayer.
Peter was first given the keys, but then he was allowed to fall into the sin of denying Christ; and so his pride was humbled by his fall. Do not be surprised, then, if after receiving the keys of spiritual knowledge you fall into various evil thoughts. Glorify our Lord, for He alone is wise: through setbacks of this kind He restrains the presumption that we tend to feel because of our advance in the knowledge of God. Trials and temptations are the reins whereby God in His providence restrains our human arrogance.
If you love Christ God, then endure as He endured, and do all that is pleasing to Him. He taught and did. Unfailingly your love should be such as does good, endures, is disturbed by nothing present, and in everything ever thanks Him not with words and tongue, but with very deeds.
Fire makes iron impossible to touch, and likewise frequent prayer renders the intellect more forceful in its warfare with the enemy. That is why the demons strive with all their strength to make us slothful in attentiveness to prayer, for they know that prayer is the intellect's invincible weapon against them.
Beguiling and deceptive is the life of the world, fruitless its labor, perilous its delight, poor its riches, delusive its honors, inconstant, insignificant; and woe to those who hope in its seeming goods: because of this many die without repentance. Blessed and most blessed are those who depart from the world and its desires.
A man is neither saved nor lost by the place he is in, but is saved or lost by his deeds. Neither a holy place nor a holy state is of use to him who does not fulfill the commandments of the Lord.
The drunkard, the fornicator, the proud - he will receive God's mercy. But he who does not want to forgive, to excuse, to justify consciously, intentionally... that person closes himself to eternal life before God, and even more so in the present life. He is turned away and not heard.
Confirm yourself in this truth: that every Divine writing that is in agreement with the path of salvation instructs, teaches, chastises, and strengthens, that our path might be ever according to God.