De rerum natura (On the Nature of Things) by Titus Lucretius Carus

In De rerum natura, Lucretius discusses the qualities of atoms and space and how they make up the world and its inhabitants. He also describes how people should conduct themselves in their relationships with each other and with nature.

War and Friendship
As an Epicurean, Lucretius opposes war and values friendship and cooperation. He carries out these twin themes in De rerum natura, painting dreadful, gruesome pictures of war and pleasant pictures of people enjoying each other's company and supporting each other. Lucretius frequently uses war imagery to illustrate scientific points about atoms and nature. Describing the occurrence of accidents, he introduces the story of Helen of Troy and the Trojan War that resulted from her abduction. In Book Three, Lucretius explains that there is no reason to fear death, using an illustration from the Peloponnesian Wars to make his point. He writes that during these horrific wars, everyone lived in fear of which side would triumph and who would subsequently rule them. According to Lucretius, this is how most people view death. Letting go of one's fear of death, however, means releasing the fear of which "side" (life or death) will win.

Complementing Lucretius' view of war is the Epicurean view of friendship. The Epicureans regarded friendship as one of the greatest and most worthwhile experiences humans can pursue in life. This idea is not, however, carried over into the realm of romantic love. Lucretius denounces surrendering to this kind of love, as it only leads people to make unwise decisions and squander their fortunes, and leaves them vulnerable to jealousy and rejection.

Religion and Science
The Epicurean rejection of religion in favor of reason and science permeates De rerum natura. Lucretius explains that people have been too quick to believe that the movements and events of nature are dictated by the gods. On the contrary, Lucretius depicts the gods as remote beings living in total peace and tranquility. They have no reason to be interested in human affairs, so it is no use to worship them or make sacrifices to them. By telling the tragic story of Agamemnon willingly sacrificing his own daughter to win the favor of the gods, Lucretius demonstrates that what humans understand to be piety is actually senseless cruelty.

Science, on the other hand, is the path to truth. Lucretius maintains that the senses are unfailing and that, combined with experience, they have the power to teach people how the world truly operates. He appeals to reason and makes methodical arguments that not only tear down existing belief systems about natural occurrences, but also seek to replace them with reasonable explanations. For Lucretius, the only worthy religion is reverence toward nature. In Book Two, he goes so far as to assert that Earth is the only true creative divinity: "So Earth alone is called 'Great Mother of Gods' / And 'Mother of Beasts' and 'She Who Formed Our Flesh.'"

Nature's Cyclical Rhythms
Throughout the poem, Lucretius affirms that nature functions in ongoing, predictable cycles. There is no death without birth, and every atom moves through a series of cycles as it converges with other atoms to create different things. In Book One, Lucretius writes, "Nothing returns to nothing; when things shatter / They all return to their constituent atoms ... / Nature restores / One thing from the stuff of another, nor does she allow / A birth, without a corresponding death." In Book Two, he comments, "So the / Whole is ever / Renewed, while mortal things exchange their lives." The cycles of nature are...