Almighty God, unto whom all hearts are open, all desires known, and from whom no secrets are hid; cleanse the thoughts of our hearts by the inspiration of Thy Holy Spirit, that we may perfectly love Thee, and worthily magnify Thy holy Name, through Jesus Christ our Lord. Amen.
Gregorian Sacramentary, A.D. 590
In this prayer of love to God, I ask you, Heavenly Father, that my heart may be cleansed. Create in me a clean heart, O God, one made of flesh, not of stone.