"My Fairy" by Lewis Carroll

This poem was written when he was 12 or 13, but still remains my favourite of all his works.

  My Fairy (1845)

I have a fairy by my side
 Which says I must not sleep,
When once in pain I loudly cried
 It said, 'You must not weep.'

If, full of mirth, I smile and grin,
 It says, 'You must not laugh';
When once I wished to drink some gin
 It said, 'You must not quaff.'

When once a meal I wished to taste
 It said, 'You must not bite';
When to the wars I went in haste
 It said, 'You must not fight.'

'What may I do?' at length I cried,
 Tired of the painful task.
The fairy quietly replied,
 And said, 'You must not ask.'

  Moral

 'You mustn't.'