Fear the judgments of God, fear greatly the wrath of the Almighty. Shrink from debating upon the works of the Most High, but search narrowly your own iniquities into what great sins you have fallen, and how many good things you have neglected. There are some who carry their devotion only in books, some in pictures, some in outward signs and figures; some have Me in their mouths, but little in their hearts. Others there are who, being enlightened in their understanding and purged in their affections, continually long after eternal things, hear of earthly things with unwillingness, obey the necessities of nature with sorrow. And these understand what the Spirit of truth speaks in them; for He teaches them to despise earthly things and to love heavenly; to neglect the world and to desire heaven all the day and night.
Imitation of Christ, III, 4:4