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 bene............