Impromptu (I)

You say you're glad I write—oh, say not so!
  My fount of song, dear friend, 's a bitter well;
  And when the numbers freely from it flow,
  'Tis that my heart and eyes o'erflow as well.
  Castalia, famed of yore,—the spring divine,
  Apollo's smile upon its current wears:
  Moore and Anacreon found its waves were wine,
  To me it flows a sullen stream of tears.