义,利也。
义,就是利。
Remembering that you are going to die is the best way I know to avoid the trap of thinking you have something to lose.
四元数的诞生,如同几何、代数、形而上学和诗歌这四位父母的奇特后代。
通过经验获得的东西比通过推理获得的东西更真实、更坚实。