author, though all his other productions had been lost:

_I dare do all that become a man,
Who dares do more, is none_.

This topic, which has been always employed with too much success, is
used in this scene with peculiar propriety, to a soldier by a woman.
Courage is the distinguishing virtue of a soldier, and the reproach of
cowardice cannot be borne by any man from a woman, without great
impatience.

She then urges the oaths by which he had bound himself to murder Duncan,
another art of sophistry by which men have sometimes deluded their
consciences, and persuaded themselves that what would be criminal in
others is virtuous in them; this argument Shakespeare, whose plan
obliged him to make Macbeth yield, has not confuted, though he might
easily have shewn that a former obligation could not be vacated by a
latter: that obligations laid on us by a higher power, could not be
over-ruled by obligations which we lay upon ourselves.

I.vii.41 (431,1)

--Whouldst thou have that,
Which then esteem'st the ornament of life,
And live a coward in thine own esteem?]

In this there seems to be no reasoning. I should read,

Or _live a coward in thine own esteem_?