Epicurus thought of justice as an agreement to prevent people harming and being harmed.

I think we do have a better understanding now of how moral thought and discourse function.

Epicurus was in favour of friendly sex but not of grand passions or marriage and children, viewing them as sources of trouble and vexation.

Oddly, since by now I've written quite a lot on early modern philosophers, I didn't care for the history of philosophy, which I thought dull and obscure, until I got a minor job writing articles for a children's encyclopedia in the history of science and began to make connections between science and philosophy.

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.

Claims like 'Slavery is wrong' are not fully common-sensical, so they must be at least partly theoretical.

There's Hobbes, who understood in the 1640s that the sovereign is not an appointee of God, or even a figure of superior virtue and wisdom, but just a functional device whose role is to keep people from hurting and killing each other.