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.
[Lat., Ingratus est, qui beneficium accepisse se negat, quod
accepit: ingratus est, qui dissimulat; ingratus, qui non reddit;
ingratissimus omnium, qui oblitus est.]