There is no single test or formula for producing moral progress anymore than there is for generating scientific truths. It is a process involving theoreticians, fact-gatherers, protestors, martyrs for the cause, authors of first- person narratives who change the way we see and evaluate the distribution of harms and benefits.

Order can arise from chaos without anyone or anything directing the process when unstable combinations of atoms perish and others persist. In the 17th century, Descartes applied this insight to cosmology, and long before Darwin presented his more rigorous ideas about variation and selection, people began to speculate more openly about the origins of life and the species in Epicurean terms.

In Western Europe and North America some things are better than they were - at least relative to their moral nadirs - such as labour legislation, the opening of the professions to women, intolerance for domestic violence, but so much is still morally unacceptable - the weapons trade, cruel and unusual punishment, economic parasitism.

Even if the gods did exist, the Epicureans argued, they didn't care about us. Rather, everything comes from nature, and all that really exists are atoms and void, moving and congregating.

For seventeenth-century astronomers, the Epicurean doctrine of multiple worlds separated by void space was seen to fit with the new Copernican system in which every star was a sun, and the universe was a vast place with no centre.

Gentlemanly, principled, helpful behaviour by older men vis-a-vis young women goes unnoticed, but it deserves real moral credit, and we could use more first-person testimony from the beneficiaries and practitioners about that too.

The life-world of human and animal experience, with colours, tastes, solid objects, is a perceptual effect of massed atoms.