"The song was Byron's Ballad"
So, we'll go no more a-roving 
  So late into the night, 
Though the heart be still as loving, 
  And the moon be still as bright. 
 
For the sword outwears its sheath,        
  And the soul wears out the breast, 
And the heart must pause to breathe, 
  And love itself have rest. 
 
Though the night was made for loving, 
  And the day returns too soon, 
Yet we'll go no more a-roving 
  By the light of the moon. 

 

Lord Byron (1788 - 1824) wrote the poem around 1817, when he was 28 or 29.