Let us therefore understand our destination; let us always remember that our common Master calls us to union with Himself.
It is especially necessary for Christians to have a pure heart, so that they may be able to see God with the eyes of the heart, as He is, with His love to us and with all His perfections,
– as well as to be able to contemplate the beauty of the angels, all the glory of the Holy Virgin, the beauty of Her soul and Her greatness, as the Mother of God, and the beauty of the souls of God’s saints, and their love to us.
We must see them as they are in themselves, we must contemplate the truths of the Christian faith, with all its sacraments, and feel their greatness; we must see the state of our own souls, and especially our sins.
An impure heart – that is, a heart occupied with earthly passions – feeds itself on the carnal desires of the eyes and worldly pride; it cannot see any of the things we have indicated.
Prayer is the lifting up of the mind and heart to God.
From this it is evident that it is quite impossible for anyone to pray whose mind and heart are attached to anything carnal – for instance, to money or to honours – or who has in his heart passions such as hatred or envy for others.
Because passions usually contract the heart, in the same way as God expands it and gives it true freedom.
It is incomprehensible how Jesus Christ is united with the sign of the Cross, and gives it the wonderful power of driving away passions, demons, and to calm the troubled soul.
It is likewise incomprehensible how the spirit of our Lord Jesus Christ is united with the bread and wine, transforming them into His own Flesh and Blood, and manifestly cleansing our soul from sins, bringing into it heavenly peace and tranquillity and making it good, gentle, humble, and full of hearty faith and hope.
[...] In order that the unbelieving heart should not think that both the sign of the Cross and the name of Christ act miraculously by themselves, apart from and independently of Christ Himself, this same Cross and name of Christ do not perform any miracles, until I see Jesus Christ with the eyes of my heart, or by faith, and until I believe with my whole heart all that which He has accomplished for our salvation.
“I am with you always, even unto the end of the world.”
John of Kronstadt (1829-1908; Russian Orthodox): My Life in Christ