The Imitation of Christ, by Thomas a Kempis, tr. by William Benham , at sacred-texts.com
When I consider Thy dignity, O Lord, and mine own vileness, I tremble very exceedingly, and am confounded within myself. For if I approach not, I fly from life; and if I intrude myself unworthily, I run into Thy displeasure. What then shall I do, O my God, Thou helper and Counsellor in necessities.
2. Teach Thou me the right way; propound unto me some short exercise befitting Holy Communion. For it is profitable to know how I ought to prepare my heart devoutly and reverently for Thee, to the intent that I may receive Thy Sacrament to my soul's health [or it may be also for the celebrating this so great and divine mystery].