Analysis of Time's Shadow

Thy life, O Man, in this brief moment lies:
Time's narrow bridge whereon we darkling stand,
With an infinitude on either hand
Receding luminously from our eyes.
Lo, there thy Past's forsaken Paradise
Subsideth like some visionary strand,
While glimmering faint, the Future's promised land,
Illusive from the abyss, seems fain to rise.

This hour alone Hope's broken pledges mar,
And joy now gleams before, now in our rear,
Like mirage mocking in some waste afar,
Dissolving into air as we draw near.
Beyond our steps the path is sunny-clear,
The shadow lying only where we are.