做事情，不能有伤害别人的坏念头；但要有警惕他人、防备他人的念头。这是在告诫与人交往思考不周的人。

The biggest regret in life is giving up what should not be given up easily, and stubbornly persisting in what should not be persisted.

It is a curious subject of observation and inquiry, whether hatred and love be not the same thing at bottom.

某人的一小步就是人类的一大步。