Few people can give what they have received, because the ancestors who paid died and can not be repaid. Accounts can only be settled between those who are alive and those who are alive in the future. Perhaps, in a long, long time, mankind can go back in time, and how will future people repay their ancestors?

If things go well, I will work in the future, do things for others. Will I pay enough for what I've gotten? How much do they deserve? It's hard to repay, and I can't help hating.