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. But in these cases we still have judgement here, that we but teach bloody instructions, which, being taught, return to plague th' inventor. This even-handed justice commends th' ingredience of our poisoned chalice to our own lips. he's here in double trust: First, as I am his kinsman and his subject, strong both against the deed; then, as his host, who should against his murderer shut the door, not bear the knife myself...(1.7.1-16)