WHAT GOOD WILL IT DO?
Thus I translate the Latin _cui bono_.

In whatever language the query is put, it is the most valuable balance-wheel ever attached to human action and speech.
The principle is old.

The pithy phrase in the shrewd Roman's mouth was two-edged, and had a sharp point.

The enterprise that led to no good was not worth beginning.
A friend of mine who has written long, much, and, so far as I can judge, always profitably, told me that in 1865 she wrought out what was, to her apprehension, the most powerful book she ever composed,--a story of the Civil War.

She was a Unionist in every thought and sentiment, and this she proclaimed; she had had unusual opportunities of seeing behind the scenes of political intrigue, and she had improved them.