The most profound ideas in mathematics often arise from the simplest observations.
The harder you work, the luckier you get.
Write what should not be forgotten.
解释：对社会有用的，创作百篇也没有害处；对社会无用的，写一章也没有好处。
You are never too old to set another goal or to dream a new dream.
La historia de América es una realidad tan desmesurada que parece inventada.