Imitation of Christ

Quare quidam Sanctorum tam perfecti et contemplativi fuerunt? quia mortificari omnino ab omnibus terrenis desideriis studuerunt, et ideo totis medullis cordis Deo inhærere, atque sibi libere vacare potuerunt. Nos nimium propriis occupamur passionibus, et de transitoriis nimis sollicitamur. Raro nam vitium unum perfecte vincimus, et ad quotidianum profectum non attendimus, ideo frigidi et tepidi remanemus. 

How came it to pass that many of the Saints were so perfect, so contemplative of Divine things? Because they steadfastly sought to mortify themselves from all worldly desires, and so were enabled to cling with their whole heart to God, and be free and at leisure for the thought of Him. We are too much occupied with our own affections, and too anxious about transitory things. Seldom, too, do we entirely conquer even a single fault, nor are we zealous for daily growth in grace. And so we remain lukewarm and unspiritual.

Imitation of Christ, I, 11:2