Samuel Taylor Coleridge - Time, Real And Imaginary

On the wide level of a mountain's head,
(I knew not where, but 'twas some faery place)
Their pinions, ostrich-like, for sails out-spread,
Two lovely children run an endless race,
A sister and a brother !
This far outstripp'd the other ;
Yet ever runs she with reverted face,
And looks and listens for the boy behind :
[Image] For he, alas ! is blind !
O'er rough and smooth with even step he passed,
And knows not whether he be first or last.

Samuel Taylor Coleridge

http://www.poemhunter.com/poem/time-real-and-imaginary/