Screw your courage to the sticking place
If we should fail?
But screw your courage to the sticking place,
And we'll not fail.
This is one time when you don't have to feel ignorant because
you don't understand what Shakespeare really meant. Although he
invented "sticking place," and though our usage derives directly
from this scene, Shakespeare never explains what the phrase
Macbeth still has cold feet; he and his wife have agreed to kill
King Duncan of Scotland, but he can't stop thinking of all the
consequences the deed might not trammel up [see THE BE-ALL
AND THE END-ALL]. Lady Macbeth, after impugning her husband's
manliness, urges him, as we might say, to "screw up his courage."
The OED suggests that Lady Macbeth's original words refer to
the twisting of a tuning peg until it becomes set in its hole. The
editor of The Riverside Shakespeare, on the other hand,
suggests that a "sticking place" is "the mark to which a soldier
screwed up the cord of a crossbow." Whether the metaphor is
musical, martial, or otherwise, Lady Macbeth's meaning is obvious
though her words are obscure: "tighten up your courage until it is
fixed in the place necessary for the murder of Duncan."