All living organisms need to be metabolized, otherwise life will stop. Civilization is the same, if it is self-closed for a long time, it will inevitably decline. Communication and mutual learning are the essential requirements for the development of civilizations. Only by communicating and learning from other civilizations and absorbing the strengths of others, To make up for one's shortcomings, in order to maintain a vigorous life.
If a civilization does not maintain its vigorous vitality, it will not absorb the strengths of others from other civilizations to make up for its own shortcomings can be derived.