Wait for it -- the last stanza -- something to think about.
I saw the Conquerors riding by
With cruel lip and faces wan;
Musing on kingdoms sacked and burned
There rode the Mongol Genghis Khan;
And Alexander, like a God,
Who sought to weld the world in one:
And Caesar with his laurel wreath;
And leading, like a star the van,
Heedless of upstretched arm and groan, Inscrutable
Dreaming of empire and alone ...
Then all perished from the earth
As fleeting shadows from a glass,
And, conquering down the centuries,
Came Christ, the Swordless, on an ass ...