開是開佛知見，示是示佛知見，悟是悟佛知見，入是入佛知見，此開示悟入乃是佛出世的本懷。

陳義孝編, 竺摩法師鑑定, 《佛學常見辭彙》

The four reasons for a Buddha's appearing in the world: to open up the treasury of truth; to indicate its meaning; to cause men to apprehend it; and to lead them into it.

A Dictionary of Chinese Buddhist Terms, William Edward Soothill and Lewis Hodous