Epicurus, founder of the school of philosophy called Epicureanism

 The Epicureans were materialists in the modern, scientific sense.They saw anxiety as the great thorn in mankind's side, and their philosophical project was to rid themselves of it, identifying that anxiety had its root in the fear of death, but as fear of death only makes sense if one believes in the permanence of the soul, and/or living a life steeped in regret (as in the regret of missed opportunities), acknowledging atomic materialism (when I am here death is not, when death is here I am not) and living life to its fullest (Carpe diem , Sieze the day!) one could have no reason to fear death, so could live their one and only life in satisfaction, and upon their death bed have no fear for what will happen next, and no regret over what they should have doneA key difference is that for the Greeks "the good life" didn't end after you were dead, but also included your legacy moving down the generations, your influence and effect on the world. It would take many years after a person's death to determine if they had in fact lived the good life. Accordingly, the Epicureans advocated moderation in things, and a balanced, "agreeable" life that pursued the "higher pleasures" of fraternity,  self improvement, and freedom from the fear of death, which they thought would result in the freedom of all fear.They accepted the physics of Democritus that the universe was composed entirely of empty space filled with atoms of differing shapes and weights that moved in non-linear paths (swerving) smashing together and latching into greater structures, composing the universe.The universe is infinite in space, time, and the number of atoms (mass) but finite in regards to the number of unique types of atoms (diversity).