Never give up. Today is hard, tomorrow will be worse, but the day after tomorrow will be sunshine.
Psychology is a science, and teaching is an art; and sciences never generate arts directly out of themselves.
Mathematics is not about numbers, equations, computations, or algorithms: it is about understanding.
數(shù)學(xué)不是關(guān)于數(shù)字、方程、計算或算法的：它是關(guān)于理解的。
The reasonable man adapts himself to the world; the unreasonable one persists in trying to adapt the world to himself. Therefore all progress depends on the unreasonable man. )