When, in 1619, John Donne urged Sir Robert Ker to remind readers of Biathanatos that it was "a Book written by jack Donne, and not by D. Donne," he probably did not expect this brief, personal message to become a fundamental part of his posthumous reputation. 1 At the time, Donne was rising rapidly through the ranks of the Church of England clergy and wanted to ensure that no one mistook it for recent work. There is no evidence that Donne made use of this binary elsewhere; indeed, Donne's sermons reflect a desire to reject extreme dichotomies in favor of a measured, if imperfect, religious and personal via media.2 Although Ben Jonson discussed Donne with William Drummond, neither is recorded as calling him "Jack," nor does lzaak W...