The Shakespeare song is sung as an Epilogue to "Twelfth Night" by the Fool. The tune it goes to is traditional in the theatre [published several places, e.g. Chappell's Popular Music of the Olden Time, p. 225. Another verse (which is a parody, I expect) is sung by the Fool in "King Lear".[He that has a little tiny wit, / With a heigh ho! the wind and the rain, / Must make content with his fortunes fit, / For the rain it raineth every day.] - the refrain's occurrence in ballads will be after this time, I suppose, but I wouldn't be surprised to learn that Shakespeare was using a verse (or a tune) already well current in his time. The unique version with the refrain was collected in West Virginia in 1931 [in Bulletin of the Folk-Song Society of the North-East no. 12 (1937), p. 10.] BTW: Wooldridge's edition of Chappell (Old English Popular Music), 1893, doesn't give the tune, because as he rather snootily says it (like some other stuff) rests "upon no better authority than tradition". [Sic.]