Analysis of I bended unto me a Bough

I bended unto me a bough of May,
    That I might see and smell:
    It bore it in a sort of way,
    It bore it very well.
    But, when I let it backward sway,
    Then it were hard to tell
    With what a toss, with what a swing,
    The dainty thing
    Resumed its proper level,
   And sent me to the devil.
   I know it did--you doubt it?
   I turned, and saw them whispering about it.