Lucretius on Optical Illusions

Article excerpt

In the first century B.C., amidst the constant turmoil and upheaval of the late Roman Republic, a poet named Titus Lucretius Catus, about whom we know next to nothing, composed one of the unlikeliest masterpieces of Western literature: an epic-length didactic poem in Latin hexameters on atomic theory and Epicurean philosophy, known to us as De Rerum Natura, "On the Nature of Things." It probably seemed as curious then as now. Prose, not poetry, was the vehicle for philosophy in the first century, and Greek, not Latin, was its proper language. Epicurus himself would, in theory, have frowned on this mode for his gospel--he disapproved of poetry--but for Lucretius, poetry was the honey that helped the bitter (and salutary) medicine of philosophy go down.

Part of Lucretius's genius is his ability to demonstrate difficult abstract concepts with concrete, everyday examples. They are so brilliantly simple that they elicit recognition even at the distance of millennia. The constant, random movement of the atoms is fixed in our minds forever with the image of dust motes dancing in a sunbeam. That a limited range of kinds of atoms can nevertheless result in the universe's infinite variety is summed up in the metaphor of the alphabet, whose two dozen or so letters can produce every word in the language.

One of the tenets of Epicurean philosophy is that sensory perception of the physical world is the basis for all knowledge. If we do misread the signals that our senses send us, Lucretius reminds us, that is our misinterpretation of the raw data. Yet, typically, Lucretius treats us, in the following passage from book four, to a closely observed description of the illusions themselves. The tangents in his poetry can have the lyrical effect of extended simile in epic--taking us out of the dense argument of the poem into the physical world--pastoral scenes, domestic vignettes, urban snapshots. What a sweep of experience is offered the reader in these few lines--we find ourselves on a moored ship, on a horse crossing a river, we splash through city streets, wonder at the starry skies, eye perspective as a geometer or draftsman, roam the landscape of dreams. We are even invited to conduct a simple experiment. (You can indeed achieve double vision by pressing under one eye--try it!)

How strangely familiar Late Republican Rome starts to seem. We have all had the experience in a stationary vehicle of feeling we are moving, or of seeing the firmament reflected in a puddle. If we don't remember ourselves spinning for the sheer dizzy joy of it, we have seen our twenty-first-century children do just that. We suddenly see Lucretius's world through our eyes. And we begin to see our own world--affluenza, greed, ambition, and anxiety are so first century--through his.

   from "De rerum natura," book four

   The scudding ship on which we sail seems to be standing fast,
   While yet a craft at anchor will appear to sail on past.
   And it is rather hills and fields that seem sternwards to fly
   When really the ship is rowing, or under sail goes skimming by.
   The stars all seem to be at rest, nailed in the vaults of heaven,
   But are perpetually in motion, since once they have arisen,
   Returning to their setting place, on far-flung paths they go
   Across the sky from end to end, with bodies all aglow.
   The sun and moon seem likewise to be frozen still, but prove
   On observation, actually to both be on the move.
   From far off, mountains jutting from the middle of the sea
   With space enough between for fleets to pass through easily,
   Seem nevertheless to be linked up into a single isle.
   Dizzy children think the columns in a peristyle
   Are going round, and that the entire court is in a spin
   Once they themselves stop turning, so that they almost begin
   To believe the house threatens to tumble in about their ears.
   And then, when Nature first above the tops of mountains rears
   The beaming sun, all red with flickering flames, the sun appears
   To be so close it's singeing them with fire. …