You cannot get through a single day without having an impact on the world around you. What you do makes a difference, and you have to decide what kind of difference you want to make.
现实主义不是复制自然，而是理解其本质。
The world owes all its onward impulses to men ill at ease; the happy man inevitably confines himself within ancient limits.
Mathematics is not just about numbers, equations, computations, or algorithms: it is about understanding.