To think twice is quite enough.

Excessive (population) growth may reduce output per worker, repress levels of living for the masses and engender strife

It is easy to hate and it is difficult to love. This is how the whole scheme of things works. All good things are difficult to achieve; and bad things are very easy to get.

Reading without thinking will confuse you.Thinking without reading will place you in danger.

What Heaven has conferred is called The Nature; an accordance with this nature is called The Path of duty; the regulation of this path is called Instruction. The path may not be left for an instant. If it could be left, it would not be the path.

He is the truly courageous man who never desponds.

A blemish may be removed from a diamond by careful polishing, but evil words once spoken cannot be effaced.