Those who are trying to lead a spiritual life have to carry on a most skillful and difficult warfare, through their thoughts, every moment of their life–that is, a spiritual warfare; il is necessary that our whole soul should be every moment a clear eye, able to watch and notice the thoughts entering our heart from the evil one and repel them; the hearts of such men should be always burning with faith, humility and love; otherwise the subtlety of the Devil finds an easy access to them, followed by a diminution of faith, or entire unbelief, and then by every possible evil, which it will be difficult to wash away even by tears.

     Do not, therefore, allow your heart to be cold, especially during prayer, and avoid every cold indifference. Very often it happens that prayer is on the lips, but in the heart cunning, incredulity or unbelief, so that by the lips the man seems near to God, whilst in his heart he is far from Him. And, during our prayers, the evil one makes use of every means to chill our hearts and fill them with deceit in a most imperceptible manner to us. Pray and fortify yourself, fortify your heart!

     Watch your heart during all your life –examine it, listen to it, and see what prevents its union with the most blessed Lord, Let this be for you the science of all sciences, and with God’s help you will easily observe what estranges you from God, and what draws you towards Him and unites you to Him. It is the evil spirit more than anything-that stands between our hearts and God; he estranges God from us by various passions, or by the desires of the flesh, by the desires of the eyes, and by worldly pride.

     The problem of our life is union with God. and sin completely prevents this; therefore flee from sin as from a terrible enemy; as from the destroyer of the soul, because to be without God is death and not life. Let us therefore understand our destination; let us always remember that our common M a s t e r calls us to union with Himself.

      Take the trouble to spend only one single day according to God’s commandments, and you will see yourself, you will feel by your own heart, how good it is to fulfill God’ s will (and God’s will in relation to us is our life, our eternal blessedness). Love God with all your heart at least as much as you love your Father, your mother, and your benefactors; value with all your strength His love and His benefits to you (go over them mentally in your heart, think how He gave you existence and with it all good things, how endlessly long He bears with your sins, how endlessly He forgives you them; for the sake of your hearty repentance, by virtue of the suffering and death upon the Cross of His only-begotten Son, what blessedness He has promised you in eternity, if you are faithful to Him); enumerate besides His mercies, which are endlessly great and manifold. Furthermore, love every man as yourself–that is, do not wish him anything that you would not wish for yourself; think, feel for him just as you would think and feel for your own self.

    The purer the heart is, the larger it is, the more able it is to find room within it for a great number of beloved ones; whilst the more sinful it is, the more contracted it becomes, and the less number of beloved it can find room for, because it is limited by self love, and that love is a false one.

    It is pleasing to God when a man begins to notice His action in the heart, because He is the Light and the Truth, whilst the Devil is powerful only through darkness, deceit, and falsehood; reveal his falsehood, place it before the light, and all will disappear!

     The future life is the perfect purity of the heart, which is now only gradually purified, and which is at present more often shut and darkened by sin and by the Devil’ s breathing into it, and only at times, under the influence of God’s grace, brightens and sees God, being united to Him most truly during prayer and in the Sacrament of Holy Communion.

     You cannot have failed to notice that all our strength lies in the heart, when the heart is light, the whole man feels at ease and happy; whilst when the heart is heavy, he feels wretched. But this relief you can only find in faith, and therefore especially in the Church, as the place where faith predominates; here God touches your heart through His cleansing grace, and gives you His easy yoke to bear. This is a great mystery, which is worth everyone’s knowing. When the heart is light, the man is ready to run and leap. This is why David “danced when he played before the ark” (I Chronicles 12:8).

    We possess a true barometer which shows the rise and fall of our spiritual life–that is, our heart. It may also be called a compass, by means of which we are guided in our voyage over the sea of this life. It shows us whither we are going–to the spiritual east, to Christ; or to the spiritual west, the dark power that has the power of death–the Devil. Only watch this compass attentively; it will not deceive, and it will show you the true way.

    Remember that you are always walking in the presence of the sweetest Lord Jesus. Say to yourself oftener: “I wish so to live that my life may gladden my Beloved, crucified for my sake on the Cross. Above all, I will take for the companion and friend of my life my Holy Beloved, Who instills everything into my heart, making me thirst for the salvation of all, rejoicing with those who rejoice, and weeping with those who weep.” This will especially comfort my Comforter, Christ. 

(Excerpts from My Life in Christ, the Diary of St. John of Kronstadt; Holy Trinity Monastery, .Jordanville,. NY; 1971.)