Given this year’s 400th anniversary of Shakespeare’s death, there was always going to be a slew of new publications; few, I suspect, will have as long-lasting an effect as John Kerrigan’s. His field of inquiry is both straightforward and complicated. It is almost retrospectively obvious that Shakespeare’s plays contain a great amount of vows, oaths, swearing both covenantual and vulgar, pledges, promises and imprecations.