And I will give them one heart, and put a new spirit within them; I will take the stony heart out of their flesh and give them a heart of flesh, that they may walk in my statutes and keep my ordinances and obey them; and they shall be my people, and I will be their God. (Ezekiel 11:19)
For thus says the high and lofty One who inhabits eternity, whose name is Holy: “I dwell in the high and holy place, and also with him who is of a contrite and humble spirit, to revive the spirit of the humble, and to revive the heart of the contrite. (Isaiah 57:15)
Archimandrite Zacharias instructs us:
Unless we endeavour to live within our heart, we remain blind to our untamed passions. The inclinations of our heart and mind remain beyond our control. We sin whether we want to or not. Sin can never attract the blessing of God, so unless we keep our hearts alive and alert, we will eventually become strangers to Him. The Scriptures say that ‘the heart is deep.’ God honours this ‘deep heart’ of man. All heaven hearkens to a deep heart athirst for God and ready to receive Him. But if our heart is indifferent to God, we are worth little more than dust and ashes. We must attend to our heart and cultivate it, for the hidden man of the heart is very precious in the sight of God. May God give us such a heart, a deep heart that is capable of divine and spiritual sensation!
We learn to enter into our ‘deep heart’ through personal prayer in our rooms and attendance at church services. And if we take courage and enter therein, we shall behold the great miracle of the union of our life with God’s Life, for this takes place in the heart of man. Indeed, the aim of our entire ascetic struggle – our fasts, vigils and prayers – is to reveal the heart, to unearth it. (Remember Thy First Love: The Three Stages of the Spiritual Life in the Theology of Elder Sophrony, p. 241-242)