Book 3.10

Besides this, no day is appointed for repayment of a benefit, as there is for borrowed money; consequently he who has not yet repaid a benefit may do so hereafter: for tell me, pray, within what time a man is to be declared ungrateful? The greatest benefits cannot be proved by evidence; they often lurk in the silent consciousness of two men only; are we to introduce the rule of not bestowing benefits without witnesses? Next, what punishment are we to appoint for the ungrateful? is there to be one only for all, though the benefits which they have received are different? or should the punishment be varying, greater or less according to the benefit which each has received? Are our valuations to be restricted to pecuniary fines? what are we to do, seeing that in some cases the benefit conferred is life, and things dearer than life? What punishment is to be assigned to ingratitude for these? One less than the benefit? That would be unjust. One equal to it; death? What could be more inhuman than to cause benefits to result in cruelty?