Some persons are alarmed and disquieted by supposing that when a bad thought comes into their minds, they sin. This is an error. We sin only when we dwell with any complacency on bad thoughts; when we entertain and do not reject them. If we have not given occasion to the entrance of a bad thought by indolence, by self-indulgent habits, by negligence in guarding our senses, i.e., our eyes and ears, and if we absolutely repel it, a thought, however bad, will rather bring us favour from God, and increase grace to us. We must not expect, in this life, to have a peace that is without combat. Holiness does not consist in being exempt from temptation, but in standing firmly against it. Be not afraid then of thoughts which in spite of yourselves come into your mind; but, as quickly as possible reject them; driving them off, as you would a wasp or gnat. Have recourse at once to prayer. Say to Christ, Help, Lord, or I perish, and He will help you to triumph against your assailants. Resist the devil, and he will fly from you, and it may be, that angels unseen, sent by God, will come and minister to you a present blessing.
- text taken from Daily Bread - Bring a Few Morning Meditations for the Use of Catholic Christians by Father Richard Waldo Sibthorp