From Such Nonsense! An Anthology, by Carolyn Wells
MR J. KEATS' PURPLE COW
"A cow of purple is a joy forever.
It's loveliness increases. I have never
Seen this phenomenon. Yet ever keep
A brave lookout; lest I should be asleep
When she comes by. For, though I would not be one,
I've oft imagined 'twould be a joy to see one."
By Carolyn Wells