On The Nature Of Things

This book lays out Epicurean cosmology and the nature of our world. Its arguments can be divided into the birth of the world, astronomy, the birth of life on Earth, and the origins of civilization.

Lucretius introduces his detailed cosmology by announcing that the ‘world,’ by which he means the sky, the sea, and the land, will collapse one day. Though this is inevitable, he does express the hope that “reasoning rather than reality [will] convince you that the whole world may give way and collapse with a horrendous crash” (Book V, lines 108-109; page 139). Lucretius also reminds us that the combination of chance and time created the world: particles traveling at random were bound to create these circumstances eventually. The gods, therefore, did not have a hand in the world’s creation.

The main elements that make up our world are earth, water, air, and fire. Lucretius shows that the world must be mortal by demonstrating how all of its component elements are mutable and weak (“soft,” as established in Book I); evidence that the world will collapse, since something that is made of mortal components cannot itself be immortal. The birth of the world was chaotic, according to Lucretius, with the four elements in imbalance and its component atoms forming a disordered cloud. From this chaos they settled into order, with each element finding the realm that suited it best (earth at the bottom because it’s the heaviest, then sea, then air, then fire forming the celestial bodies).

Since the sky is a part of our world in this model, Lucretius must also explain astronomy. He tells us that the moon, the sun, and the stars are all fixed on spheres, which spin due to gusts of wind of various speeds (which explains why they each travel at different speeds).

Lucretius is cautious in this section, since so much about astronomy is unknowable to him. For example, when discussing the sun, moon, and stars, he opines that all of them, though very far away, are exactly the size and brightness they appear to be from earth. He is uncertain how the sun can be so hot and bright despite its small size, but offers a few possibilities, including: “It is possible that this one free-flowing fountain for the whole world has been opened to pour out light in a gushing stream” (Book V, lines 596-598; page 153).

From astronomy, Lucretius moves to the origins of life on Earth. He believes that plants appeared first, and that animals were born from the Earth. Since conditions were different on the young Earth, wombs grew straight from the ground, and the Earth produced milk spontaneously, the way mothers do. This is the source of all creatures, but the planet has now aged out of its fertile stage and no longer produces new animals. Lucretius believes in the survival of the fittest, and he tells us that the Earth once produced many bizarre, grotesque animals that failed to survive.

The earliest humans, we’re told, adhered largely to the ‘caveman’ image that endures to this day: they were tough and nomadic, hiding from predators at night. Using rudimentary weapons for hunting, and not yet having a society to speak of, they had not yet created warfare. Gradually, humans invented clothing and fire, and led more settled lives that led to early societies that maintained order through honesty rather than rule of law: “Otherwise the human race would have been entirely extinguished at that early stage…” (Book V, lines 1027-1028; page 164). At about this time, humans also invented language.

As society progressed, social stratification emerged, with some people becoming kings and building great cities. This new form of power caused the invention of warfare, and societies overthrew their kings and invented laws.

Lucretius also tells us about the birth of religion, with early humans trying to explain natural phenomena that were beyond their understanding. This is the same superstition he has warned us about from the beginning, and he rues the invention of religion as an unnecessary burden upon mankind. Lucretius also describes the discovery of metals, and the invention of weaving, agriculture, and music.

Reflecting upon all of these inventions, Lucretius laments that innovation and progress, while helpful at first, ultimately cause jealousy, violence, and greed. Lucretius concludes his reflections by emphasizing that all human inventions, whether practical or aesthetic, came about through slow progress rather than a moment of creation.