Neither rhyme nor reason
But I pray, sir, why am I beaten?
Dost thou not know?
Nothing, sir, but that I am beaten.
Shall I tell you why?
Ay, sir, and wherefore; for they say, every why hath a
Why, first, for flouting me, and then wherefore, for
urging it the second time to me.
Dromio:The Comedy Of Errors Act 2, scene 2, 39–48
Was there ever any man thus beaten out of season,
When in the why and the wherefore is neither rhyme nor reason?
The phrase "neither rhyme nor reason" will show up again in Shakespeare—in As You Like It (Act 3, scene 2) and, with variation, in The Merry Wives of Windsor (Act 5, scene 5). The linking of these two alliterative nouns is at least as old as the poet John Skelton, who in the 1520s wrote that "For reason can I none find/ Nor good rhyme in your matter." The phrase as we use it today, however, is first preserved in Shakespeare's earliest comedy. (The earliest citation in the OED is from 1664.)
The Comedy of Errors, an apprentice work, is Shakespeare's attempt to adapt Latin comedy to the English stage. In all the old comedies, masters constantly threaten to—or actually do—abuse their servants, and Shakespeare's Antipholus of Syracuse is no exception. When the servant Dromio begs for an explanation of what he's done wrong, Antipholus says that Dromio is "flouting" (mocking) him by denying having said something Antipholus is sure Dromio said. The confused Dromio, sure that he hasn't said what Antipholus thinks he said, finds "neither rhyme nor reason" in the accusation—that is, neither order nor inherent sense. The confusion, though neither knows it, is due to the existence of twin Antipholuses and Dromios; farcical episodes of mistaken identity account for the entire plot of the play.