"the [deepest] desire of your heart is itself your [unceasing] prayer"

"'All my desire is before you, Lord.  Not before human beings, who cannot see my heart, but before you is my desire.'  Let your desire too be before him, and there your Father, who sees in secret, will reward you.  This very desire is your prayer, and if your desire is continuous, your prayer is continuous too.  The apostle meant what he said, Pray without ceasing (1 Thes 5:17)."

     St. Augustine, Ennarationes in Psalmos 37.14 (v. 10), trans. Maria Boulding, O.S.B., WSA III/16 (Hyde Park, NY:  New City Press, 2000), 156-157.  Heading from the translation in the Liturgy of the hours (Office of readings, Friday, Third Week of Advent).

"Et ante te est omne desiderium meum.  Non enim ante homines, qui cor videre non possunt:  sed ante te est omne desiderium meum.  Sit desiderium tuum ante illum; et Pater qui videt in occult, reddet tibi (Matth. vi, 6).  Ipsum enim desiderium tuum, oratio tua est:  et si continuum desiderium, continua oratio.  Non enim frustra dixit Apostolous, Sine intermissione orantes (1 Thess. V, 17)."

     PL 36, col. 404.  Cf. the new critical edition in CSEL 93, ed. Clemens Weidmann (2003- ), as well as CCSL 39, ed. Eligius Dekkers and Iohannes Fraipont (1956).