"On the Nature of Things" is a first-century BC long didactic poem written in Latin as "De rerum natura" by the Roman poet and philosopher Lucretius that sets forth the physical theory of the Greek philosopher Epicurus. Epicurus taught that the world could be understood by reason and that religion only arouses unnecessary fear. Lucretius denounced popular beliefs in deities and supernatural creatures.

The staying power of "On the Nature of Things" is unquestionable. The work has been, over the centuries, both widely influential on the greatest writers and widely reviled. Quickly dubbed atheistic by early Christian fathers, the book continued to provoke negative reactions from Catholic theologians for nearly a millennium.

Rediscovered during the Renaissance, the work became an oft-quoted source of inspiration for figures as diverse as Giordano Bruno in Italy, Michel de Montaigne in France, and Edmund Spenser in England.