We ought to be careful never to do anything rashly or carelessly, or anything at all for which we cannot give a reasonable ground.
For though a reason for our action is not given to everyone, yet everybody looks into it. Nor, indeed, have we anything to excuse ourselves with. For though there is a sort of natural force in every passion of ours, yet that same passion is subject to reason by the law of nature itself, and is obedient to it.
Therefore it is the duty of a careful watchman to keep a lookout, so that passion may not outrun reason or utterly forsake it. Otherwise, by outstripping it, confusion be caused, and reason be shut out, and come to nothing by such desertion.
Disquiet destroys consistency. Withdrawal from rationality shows cowardice and implies indolence. For when the mind is disquieted, passion spreads wide and far, and in a fierce outburst will not stand for the reins of reason and cannot be turned back by its driver. Thus, as a rule, not only is the soul perturbed and reason lost, but the face turns red with anger or lust, it grows pale with fear, it cannot contain itself in pleasure, and cannot bear joy.
When this happens, then our natural judgment and weight of character is cast aside, and we can no longer keep that consistency which alone in deed and thought can keep up its own authority and what is appropriate.
Based on Saint Ambrose