A famous nonsense poem by Gelett Burgess. He was quite well known for his short humorous poems, of which this one is probably the most famous, overshadowing even his Goops. Burgess liked to give his poems long rhyming names, small poems in their own rights. The full title of Purple Cow is nearly as long as the poem itself:
The Purple Cow's Projected Feast: Reflections on a Mythic Beast, Who's Quite Remarkable, at Least.
I never saw a purple cow,
I never hope to see one;
But I can tell you anyhow,
I'd rather see than be one.
-- The Lark number 1, May 1, 1895
The original poem became so popular that he later wrote a sequel:
Confession: and a Portrait, Too, Upon a Background that I Rue!
Ah, yes, I wrote "The Purple Cow"--
I'm sorry now I wrote it!
But I can tell you anyhow,
I'll kill you if you quote it.
-- The Lark, number 24, April 1, 1897
This is a shining example of a palinode.