Yet there is another, interior kind of prayer without ceasing, namely, the desire of the heart. Whatever else you may be doing, if you but fix your desire on God’s Sabbath rest, your prayer will be ceaseless. Therefore, if you wish to pray without ceasing, do not cease to desire.
The constancy of your desire will itself be the ceaseless voice of your prayer. And that voice of your prayer will be silent only when your love ceases. For who are silent? Those of whom it is said: Because evil has abounded, the love of many will grow cold.
The chilling of love means that the heart is silent; while burning love is the outcry of the heart. If your love is without ceasing, you are crying out always; if you always cry out, you are always desiring; and if you desire, you are calling to mind your eternal rest in the Lord.
” —St. Augustine