He is ungrateful who denies that he has received a kindness which has been bestowed upon him; he is ungrateful who conceals it; he is ungrateful who makes no return for it; most ungrateful of all is he who forgets it.
Ingratus est, qui beneficium accepisse se negat, quod accepit: ingratus est, qui dissimulat; ingratus, qui non reddit; ingratissimus omnium, qui oblitus est.
Original text (Latin)