There MUST be a genuinely and utterly self-sacrificing act recorded in human history somewhere. You are young. You have many years before you. Search one out. If you choose.
Circumstances alter cases.
I suppose that if there was no audience to observe the act, the man wouldn't perform it. Because they couldn't BEAR to see a fellow-being struggling in the water and not jump in and help. It would give THEM pain. They would save the fellow-being on that account. They strictly obey the law which I have been insisting upon.