Philosopher and historian George Santayana once commented that those who don't know history are doomed to repeat the mistakes of their predecessors. This statement is not always correct. In some cases, psychologists have learned about past mistakes, but they will still repeat them.

History is vast, and no one can know all the historical truths all his life. There is no shame in not knowing them. However, history is always in a cycle, so reading history books can distinguish the past from the present and make people "wise". If a nation forgets its own history, it is a sad thing, because it may repeat the same mistakes and suffer deep pain again. It is said that the scar healed and the pain was forgotten.