Your self-worth is determined by you. You don’t have to depend on someone telling you who you are.

The mathematician does not study pure mathematics because it is useful; he studies it because he delights in it and he delights in it because it is beautiful.

我告诉你，德并不是用钱买来的，但是德却可以带来金钱。

系统的稳定性由其根的行为决定。