我从来没有见过这样阴郁而又光明的日子。

哲学的本质不是拥有真理，而是寻找真理。

I'm not going to keep on knocking that old door that doesn't open for me. I'm going to create my own door and walk through that.

可能近似正确（PAC）学习的概念在计算学习理论中具有基础性意义。