The Imitation of Christ, by Thomas a Kempis, tr. by William Benham [1886], at sacred-texts.com
Thou must frequently betake thee to the Fountain of grace and divine mercy, to the Fountain of goodness and all purity; to the end that thou mayest obtain the healing of thy passions and vices, and mayest be made stronger and more watchful against all temptations and wiles of the devil. The enemy, knowing what profit and exceeding strong remedy lieth in the Holy Communion, striveth by all means and occasions to draw back and hinder the faithful and devout, so far as he can.
2. For when some set about to prepare themselves for Holy Communion, they suffer from the more evil suggestions of Satan. The very evil spirit himself (as is written in Job), cometh among the sons of God that he may trouble them by his accustomed evil dealing, or make them over timid and perplexed; to the intent that he may diminish their affections, or take away their faith by his attacks, if haply he may prevail upon them to give up Holy Communion altogether, or to come thereto with lukewarm hearts. But his wiles and delusions must not be heeded, howsoever wicked and terrible they be; but all his delusion must be cast back upon his own head. The wretch must be despised and laughed to scorn: neither must Holy Communion be omitted because of his insults and the inward troubles which he stirreth up.
3. Often also too much carefulness or some anxiety or other touching confession hindereth from obtaining devotion. Do thou according to the counsel of wise men, and lay aside anxiety and scruple, because it hindereth the grace of God and destroyeth devotion of mind. Because of some little vexation or trouble do not thou neglect Holy Communion, but rather hasten to confess it, and forgive freely all offences committed against thee. And if thou hast offended any man, humbly beg for pardon, and God shall freely forgive thee.
4. What profiteth it to put off for long time the confession of thy sins, or to defer Holy Communion? Cleanse thyself forthwith, spit out the poison with all speed, hasten to take the remedy, and thou shalt feel thyself better than if thou didst long defer it. If to-day thou defer it on one account, to-morrow perchance some greater obstacle will come, and so thou mayest be long time hindered from Communion and become more unfit. As soon as thou canst, shake thyself from thy present heaviness and sloth, for it profiteth nothing to be long anxious, to go long on thy way with heaviness of heart, and because of daily little obstacles to sever thyself from divine things: nay it is exceeding hurtful to defer thy Communion long, for this commonly bringeth on great torpor. Alas! there are some, lukewarm and undisciplined, who willingly find excuses for delaying repentance, and desire to defer Holy Communion, lest they should be bound to keep stricter watch upon themselves.
5. Alas! how little charity, what flagging devotion, have they who so lightly put off Holy Communion. How happy is he, how acceptable to God, who so liveth, and in such purity of conscience keepeth himself, that any day he could be ready and well inclined to communicate, if it were in his power, and might be done without the notice of others. If a man sometimes abstaineth for the sake of humility or some sound cause, he is to be commended for his reverence. But if drowsiness have taken hold of him, he ought to rouse himself and to do what in him lieth; and the Lord will help his desire for the good will which he hath, which God specially approveth.
6. But when he is hindered by sufficient cause, yet will he ever have a good will and pious intention to communicate; and so he shall not be lacking in the fruit of the Sacrament. For any devout man is able every day and every hour to draw near to spiritual communion with Christ to his soul's health and without hindrance. Nevertheless on certain days and at the appointed time he ought to receive the Body and Blood of his Redeemer with affectionate reverence, and rather to seek after the praise and honour of God, than his own comfort. For so often doth he communicate mystically, and is invisibly refreshed, as he devoutly calleth to mind the mystery of Christ's incarnation and His Passion, and is inflamed with the love of Him.
7. He who only prepareth himself when a festival is at hand or custom compelleth, will too often be unprepared. Blessed is he who offereth himself to God for a whole burnt-offering, so often as he celebrateth or communicateth! Be not too slow nor too hurried in thy celebrating, but preserve the good received custom of those with whom thou livest. Thou oughtest not to produce weariness and annoyance in others, but to observe the received custom, according to the institution of the elders; and to minister to the profit of others rather than to thine own devotion or feeling.