Chapter 199
On Methods in Prayer and the Gift of Grace
In the first letter you write well about prayer, namely: that the methods in prayer—how to hold attention and what posture to give the body and certain of its members—are not the essential matter in prayer; let each person hold himself as feels best.
The chief concern in prayer is that it should flow from the heart. True prayer of the heart is a gift of grace, bestowed through the sacraments of confession or communion. And after such a gift is given, it is warmed by these same sacraments. The distinguishing mark of this gift is the continuity of prayer, which is expressed as a feeling toward God, sometimes in the words of prayer, and sometimes without words.
What grace gives, your own effort can in no way give. It only prepares you to receive the gift—and after receiving it, sustains it—together with the sacraments.
(Letter 915. Vol. 5, pp. 195–196)