The be-all and the end-all
If it were done, when 'tis done, then 'twere well
It were done quickly. If th' assassination
Could trammel up the consequence, and catch
With his surcease, success: that but this blow
Might be the be-all and the end-all—here,
But here, upon this bank and shoal of time,
We'd jump the life to come.
Macbeth ponders assassinating King Duncan of Scotland, whose shoes he intends to fill [see CHANCE MAY CROWN ME]. If simply killing the king were all there was to it, he tells himself, there'd be no problem. But there are bound to be unpredictable and uncontrollable consequences, both in this life ("upon this bank and shoal of time") and in the "life to come." Yet he'd "jump" (risk) the spiritual penalties if he could be sure of immediate success here and now.
TRAMMEL UP THE CONSEQUENCE
"Trammel up the consequence" is ill understood, which hardly comes as a surprise. A "trammel," in Shakespeare's day, most often meant a "fishing net"; "to trammel up" therefore meant to catch up in a trammel net. (Another obsolete sense of "to trammel," current in the sixteenth century, is "to bind up a corpse"—a sense eerily appropriate here.) When Macbeth doubts whether the assassination could "trammel up the consequence," therefore, he doubts that the act of killing Duncan will catch up in itself, as in a net, the consequences of that action.
Macbeth, by the way, seems to have invented the word "assassination"—this is at least the first recorded use.
BE-ALL AND END-ALL
We use "the be-all and the end-all" in two rather different ways, neither of which pays much respect to Macbeth's intention. On one hand, the be-all and the end-all is something superlative in its category—a paragon or an extreme. On the other hand, the be-all and the end-all is an all-consuming project or passion—an idée fixe. Both uses, which meet somewhere in the vicinity of "the last word in the matter," pick up on the literal meaning of Macbeth's words while slighting the context. Macbeth speaks of an action, not a person or thing; he wonders if that action will be all that is required and end all that he must go through to be king. We refer to what is all it can possibly be and ends all competition, or to something that overrides all the normal limits. Macbeth would like his deed to be limited, while we admire a nearly unlimited excellence, or a passion without bounds.