In words of boastfulness and self-justification there always lie concealed contrariness and pride, from which God turns away. After sinning one ought immediately to 'flee.' But you say, where? To the calm haven of heartfelt repentance.
A true Christian is made by faith and love toward Christ. Our sins do not in the least hinder our Christianity, according to the word of the Savior Himself. He deigned to say: not the righteous have I come to call, but sinners to salvation; there is more joy in heaven over one who repents then over ninety righteous ones. Likewise concerning the sinful woman who touched His feet, He deigned to say to the Pharisee Simon: to one who has love, a great debt is forgiven, but from one who has no love, even a small debt will be demanded. From these judgments a Christian should bring himself to hope and joy, and not in the least accept an inflicted despair. Here one needs the shield of faith.
When the attention of the mind is fixed in the heart it is possible to control what happens in the heart, and the battle against the passions assumes a rational character. The enemy is recognized and can be driven off by the power of the Name of Christ.
You write that after Communion you felt well. Glory be to God, Who comforts our unworthiness. And as regards the fact that this soon passed, here also is seen His fatherly providence for us. For continual consolation enfeebles the soul and makes it slothful, or leads to even greater harm. That is why the Lord takes it away quickly and again makes us feel our weakness, our helplessness, and our sinfulness. We must humble ourselves more, reproach ourselves, offer repentance for our sins, and not desire consolations, but patiently endure what God allows. Dryness and cooling of fervor are also permitted on account of vainglory.
Among the virtues which must be instilled in a child's heart with special persistence, an important and fundamental place belongs to truthfulness, that is to say, a feeling of love for truth and an aversion towards falsehood. After obedience, this virtue should be given second place. If falsehood is the root of all sin, truth is the beginning and foundation for nearly all virtues, and for this reason parents must direct their attention primarily at nurturing truthfulness in children.
I must tell you that annoying incidents are unavoidable in this life. Those who are experienced in the spiritual life say that such incidents can even bring profit to the soul. Through annoying incidents we come to recognize that we are impatient - and if we are impatient, that means we are proud. And this awareness should dispose us to self-reproach and repentance, and to asking mercy from the Lord in prayer. But without annoying incidents a man is inclined to conceit.
Sin, to one who loves God, is nothing other than an arrow from the enemy in battle. The true Christian is a warrior fighting his way through the regiments of the unseen enemy to his heavenly homeland.
If the saints, who had attained passionlessless, had to be vigilant over themselves so as not to fall from their state of grace - then all the more is daily attentiveness and concern over our eternal salvation necessary for us sinners. The fact that we are still alive means that the Lord patiently endures our sins and awaits our amendment, and if someone lawfully labors for his salvation, the Lord takes him at a time when he becomes worthy of God’s mercy.
To pray with self-constraint is in our power, whereas to pray with compunction depends upon God. We must pray with what prayer we can, and for our self-constraint God will give us compunction also in due time, when this is pleasing to Him.