The beginning of all temptation lies in a wavering mind and little trust in God, for as a rudderless ship is driven hither and yon by waves, so a careless and irresolute man is tempted in many ways. Fire tempers iron and temptation steels the just. Often we do not know what we can stand, but temptation shows us what we are. Above all, we must be especially alert against the beginnings of temptation, for the enemy is more easily conquered if he is refused admittance to the mind and is met beyond the threshold when he knocks.
–Saint Francis de Sales (1567-1622)