E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Neither rhyme nor reason. Fit neither for amusement nor instruction. An author took his book to Sir Thomas More, chancellor in the reign of Henry VIII., and asked his opinion. Sir Thomas told the author to turn it into rhyme. He did so, and submitted it again to the lord chancellor. Ay! ay! said the witty satirist, that will do, that will do. Tis rhyme now, but before it was neither rhyme nor reason.