Never put off till tomorrow what you can do today.

Philip Dormer Stanhope

Zeal without knowledge is a runaway horse.

熱意はあっても知識に裏打ちされていなければ危険

A little knowledge is a dangerous thing.
  Alexander Pope

Crude tactics are the source of big injury.
生兵法は大けがのもと

He who knows best knows how little he knows.

Thomas Jefferson

He who hath many friends hath none.

Aristotle