From Gaily the Troubadour (1936), by Arthur Guiterman.

On the Vanity of Earthly Greatness

The tusks that clashed in mighty brawls
Of mastodons, are billiard balls.

The sword of Charlemagne the Just
Is ferric oxide, known as rust.

The grizzly bear whose potent hug
Was feared by all, is now a rug.

Great Caesar’s bust is on the shelf,
And I don’t feel so well myself.