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至今一切社會的歷史都是階級斗爭的歷史，即剝削階級和被剝削階級之間、統(tǒng)治階級和被壓迫階級之間斗爭的歷史。

The difference between theory and practice is that in theory, there is no difference between theory and practice, but in practice, there is.

數(shù)學(xué)是為數(shù)學(xué)家而寫的。

To conquer fear is the beginning of wisdom.

The essence of mathematics is not to make simple things complicated, but to make complicated things simple.