Interior peace is of two kinds: one in the heart or will and the other in the mind or intellect. They are closely connected but they are not the same. Peace of heart for the believing Christian is the absence of conflict between his will and that of others and ultimately between his will and the will of God. My heart is at peace when I want what God wants, when I desire only what He desires. It is in this sense that the inspired writer asks and does not have to answer his own question addressed to God, “Who has ever resisted Your will, O Lord, and been at peace?” There was no need for a reply. The answer is no one. – Fr. John Hardon