Bitterness and sweetness come from the outside world, while strength comes from the heart, and comes from a person's own efforts. ——Einstein

Solving the problem of language evolution is as difficult as solving the mystery of species evolution; language evolution is not only a social phenomenon, but also a natural phenomenon, and it is also the development and history of human mind. The result of cultural evolution; because the origin and change of language have its internal causes and external influences, this increases the complexity of language evolution issues. ——Zhou Haizhong

If a person lacks something higher and stronger than all external influences, then a serious cold will be enough to make him lose his normal state and make him think of birds as soon as he sees them. Owls, when they hear a sound, they think it is a dog barking. At such a time, all his optimism or pessimism, and the resulting thoughts of greatness and smallness, become purely pathological and nothing more.

——Chekhov