Early each day to the steps of St Paul's
A bird-woman comes, about six.
Since the start of the time when she set up her stalls
The pigeons have borne many chicks.
"Come feed the little birds! Let them lay eggs!
Feed them, and show that you cared!"
But somehow the food supply's growing as x
While the populace grows as x squared.

Deep inside the cathedral, the priest Thomas Malthus
Is turning within his grave,
Although you can't see him, his spectre comes running,
And this is the lecture he gave:

"Feed the birds? Silence it, please!
Overcrowding leads to disease!
Bear in mind for you and them both
Expo... nential... populace growth."