On the Nature of the Universe
L. plans to tell the ultimate realities of heaven and the gods, to reveal that atoms make up everything. He claims that Epicurus was the first to not cower at the unknown of nature but he investigated to understand it and then told us what can and cannot be and told us things' boundaries, thereby defeating superstition and "we by his triumph are lifted level with the skies." L. assures us that E's system is not impious or "on the path of sin," saying that more often superstition causes sinful deeds. L. says the prophets easily wreck people's happiness with fear, also the fear of eternal punishment after death, but E. shows gives us strength to resist this fear by showing there is a limit to our troubles.
He mentions Ennius's description of Hell and reincarnation. L. had to coin philosophical terms in Latin. The dread and darkness of the mind is dispelled by understanding the inner workings of nature. For this end, the starting point is the principle that nothing is ever created by divine power out of nothing. L. thinks that people are so fearful because they see things they don't know the cause of so they think the gods caused them. "if things were ... seed," pg. 14. Otherwise, things would be born from anywhere, but we see that things are born from specific seeds, where there exists the right material, the right kind of atoms. Also, there are proper times for created things to be born because the harshness of seasons prevent the atoms from entering generative unions, otherwise, they would spring up at all times. Also, things grown slowly because they need the proper atoms to accumulate, otherwise, things would just suddenly get large. So it is a fair inference that each is increased and nourished by its own raw material. Living things need specific food to grow or sustain life, this indicates that many elements are common to many things instead of a non-atomic theory. Also, the variety of living things would be limited under the atomic theory, because of its particular material determines what is made, and we do not experience men like gods and in other forms, and finally, we increase the productivity and quality of our crops by action which wouldn't be necessary if things could arise from nothing.
The second great principle is that things break down into atoms not to nothing. Things need force to break it apart, if something were perishable in all parts it could disappear suddenly. Things will exist until something forces apart its links. Since time is limitless all mortal things would come to an end at some point, if they became nothing where could Venus get the material to create new things? (since above it is shown that things aren't created from nothing). He speaks of immortal bodies that renew the things of the universe, and he mentions Venus doing this also). Atoms more or less tightly fastened together also explain why one cannot destroy anything with the same force. Last, rains exhaust themselves but make the crops grow, the crops make us grow and produce offspring, so nature repairs one thing from another, one thing is born with the aid of another's death. That atoms can't be seen is immaterial, wind can't be seen but it has the same effects on bodies in force and carrying thing in its eddies as a flood of water does.
We can't see the info of the other senses, and since nothing can touch or be touched except physical bodies they must be caused by physical bodies. Moisture enters and leaves things without our ever seeing it do so. Over time things wear away, like walk paths, etc., though we don't see what is taken away. There is empty space in things. Things couldn't move if there wasn't. "For the distinctive action ... obstruction." Observation indicates that solids are actually porous, like water seeping through rock in a cave. Food goes throughout our bodies. Sounds pass through walls. Cold gets down to the bones. A ball of wool weighs less than the same volume of iron. "it is the function ... weightless." Therefore, there is empty space in things. When two objects are moved apart it takes a while for the air to move "one spot after another" to fill that empty space, it is not already there and condensed. "The existence of ... whatever" pg. 20.
L. counts space and matter as two distinct substances.