集合论的悖论不应被视为理论本身的不一致，而应被视为表明某些被认为有效的推理方法实际上并非如此。

朋友都是有共通点的 (物以类聚)。

"The only thing necessary for the triumph of evil is for good men to do nothing."

Necessity knows no law.

A scientist’s work is never done.

Safety must always come first in mining operations.