From Wikipedia: **Siphonaptera** is a name used to refer to the following rhyme by Augustus De Morgan (_Siphonaptera_ being the biological order") to which fleas belong): > Great fleas have little fleas upon their backs to bite 'em, > And little fleas have lesser fleas, and so _ad infinitum_. > And the great fleas themselves, in turn, have greater fleas to go on; > While these again have greater still, and greater still, and so on. "Siphonaptera" comes from the Greek words for "siphon" (a hollow tube") and "without wings". The rhyme appears in De Morgan's _A Budget of Paradoxes_ (1872) along with a discussion of the possibility that all particles may be made up of clusters of smaller particles, 'and so down, for ever'; and similarly that planets and stars may be particles of some larger universe, 'and so up, for ever'. The lines derive from Jonathan Swift's long satirical poem "On Poetry: A Rapsody" of 1733: > The Vermin only teaze and pinch > Their Foes superior by an Inch. > So, Nat'ralists observe, a Flea > Hath smaller Fleas that on him prey, > And these have smaller yet to bite 'em, > And so proceed _ad infinitum_: > Thus ev'ry Poet, in his Kind > Is bit by him that comes behind. Lewis F. Richardson adapted the poem to meteorology in 1922: > Big whirls have little whirls > That feed on their velocity, > And little whirls have lesser whirls > And so on to viscosity ...