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 outspread,
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:
For he, alas! is blind!
O'er rough and smooth with even step he pass'd,
And knows not whether he be first or last.
Source: Bartleby.com (archived copy)