So, nat'ralists observe, a flea
Hath smaller fleas that on him prey,
And these have smaller still to bite 'em
And so proceed ad infinitum.

Adapted in | Big whirls have little whirls, That feed on their velocity; And little whirls have lesser whirls, And so on to viscosity. | Lewis Fry Richardson, Weather Prediction by Numerical Process (1922).