Three Canzonets, the words from Byron's Hebrew Melodies

My soul is dark - Oh! quickly string
  The harp I yet can brook to hear;
And let thy gentle fingers fling
  Its melting murmurs o'er mine ear. --
If in this heart a hope be dear,
  That sound shall charm it forth again --
If in these eyes there lurk a tear, 
  'Twill flow -- and cease to burn my brain --

But bid the strain be wild and deep,
  Nor let thy notes of joy be first:
I tell thee -- Minstrel! I must weep,
  Or else this heavy heart will burst --
For it hath been by sorrow nurst,
  And ached in sleepless silence [long]1 --
And now 'tis doom'd to know the worst,
  And break at once -- or yield to song.