6 ideas
Matter is never created from non-being nor destroyed into nothingness; if things could arise from nothing, any kind of thing could spring from any source at any time without seeds or seasons. Because we observe that specific things require specific origins and grow at fixed rates, there must be conserved indestructible material underlying all change.
Reality consists of only two fundamental things: solid eternal particles too small to split further, and empty space through which they move. All apparent variety in the world is just different arrangements, motions, and combinations of these unchanging atoms within the void.
Atoms falling through the void occasionally deviate from their straight downward paths by a tiny, uncaused amount. This minimal swerve allows atoms to collide and form things, and it breaks the chain of mechanical determinism, leaving room for free will in living creatures.
Mind and spirit are made of especially fine, fast-moving atoms distributed through the body, not an immaterial essence. Because the soul is physical and dissolves when the body's atoms disperse at death, it cannot survive or feel anything afterward, so fear of punishment after death is groundless.
Human misery stems largely from fear of the gods and of death, both rooted in ignorance of how nature actually works. By demonstrating that physical phenomena have ordinary material causes rather than divine intervention, one removes the foundation of terror and achieves tranquility.
Even if gods exist, they live in perfect serene detachment and take no part in creating or governing the world or in rewarding and punishing people. Viewing the cosmos this way means storms, plagues, and disasters are natural events, not signs of divine anger to be appeased.