Human beings of all societies in all periods of history believe that their ideas on the nature of the real world are the most secure, and that their ideas on religion, ethics and justice are the most enlightened. Like us, they think that final knowledge is at last within reach. Like us, they pity the people in earlier ages for not knowing the true facts. Unfailingly, human beings pity their ancestors for being so ignorant and forget that their descendants will pity them for the same reason.