By prayer the soul is cleansed from sin, replenished with charity, confirmed in faith, strengthened, and refreshed in spirit. Prayer establishes the inward man, pacifies the heart, knows the truth, conquers temptations, expels sorrow, renews the senses, stirs up languishing virtue, puts to flight tepidity, and scours the rust of vices. In prayer, the quick sparkles of celestial desires are incessantly sent forth, from the burning coals of divine love. The privileges of prayer are rare, the prerogatives admirable. Prayer unlocks the gates of heaven, manifests divine secrets, and always finds free access to the ears of God.
St. Peter of Alcantara (Spiritual Director of St. Teresa of Avila)