I thought of Thee, my partner and my guide,
As being past away. -Vain sympathies!
For backward, Duddon! as I cast my eyes,
I see what was, and is, and will abide;
Still glides the Stream, and shall not cease to glide;
The Form remains, the Function never dies;
While we, the brave, the mighty, and the wise,
We Men, who in our morn of youth defied
The elements, must vanish; -be it so!
Enough, if something from our hands have power
To live, and act, and serve the future hour;
And if, as toward the silent tomb we go,
Through love, through hope, and faith's transcendent dower,
We feel that we are greater than we know.

Alfred Lord Tennyson

http://www.poemhunter.com/poem/after-thought-3/