By prayer I mean not that which is only in the mouth, but that which springs up from the bottom of the heart. In fact, just as trees with deep roots are not shattered or uprooted by storms… in the same way prayers that come from the bottom of the heart, having their roots there, rise to heaven with complete assurance and are not knocked off course by the assault of any thought. That is why the Psalm says, “Out of the deep have I called unto Thee, O Lord.”

The Book of Psalms