He that is hasty to give credit is lightminded; and he that sins shall offend against his own soul.
All Commentaries on Wisdom of Sirach 19:4 Go To Wisdom of Sirach 19
Rabanus Maurus
AD 856
"One who trusts lightly will be harmed, and one who sins against his own soul will suffer even worse harm." Note that this statement does not contradict that of the apostle, who says regarding charity, "It bears all, believes all, hopes all. Charity will never end," since here the perfection of a good will is present, always ready for any good work. The other statement, rather, describes levity of soul, always changeable and lacking in stability. For this reason it is written elsewhere, "The fool changes like the moon." One, therefore, who with itching ears lets himself be easily convinced, stops listening to the truth and turns to fables will suffer harm in both his intelligence and his virtue, and one who harms his own soul will be considered a fool.