Nicene and Post-Nicene Fathers: Series II/Volume XI/John Cassian/Conferences of John Cassian, Part III/Conference XX/Chapter 10
Chapter X.
How the recollection of our sins should be avoided.
Wherefore we must endeavour to rouse ourselves to this praiseworthy contrition, by aiming at virtue and by the desire for the kingdom of heaven rather than by dangerous recollections of sins, for a man is sure to be suffocated by the pestilential smells of the sewer as long as he chooses to stand over it or to stir its filth.