Right and wrong are not simply matters of evolutionary impacts and what is natural.

The supposed revelations of God to humanity through Christ, or the word of God to Mohammed through the angel Gabriel, had the power they did because they indicated new truths, new directions for followers.

Trade has played a vital role in the social evolution of humankind. It allowed people to specialise, which raises both skill levels and efficiency. It brought people from different lands together, co-operating rather than competing over resources.

The optimist underestimates how difficult it is to achieve real change, believing that anything is possible and it's possible now. Only by confronting head-on the reality that all progress is going to be obstructed by vested interests and corrupted by human venality can we create realistic programmes that actually have a chance of success.

Seek first what is true and of value, and then whatever happiness follows will be of the appropriate quantity and, more importantly, quality.

If we find it hard to believe that winning millions might not be so lucky after all, we just don't have a good enough imagination. If I fantasise about winning the lottery, it doesn't take long before all sorts of worrisome potential consequences occur to me.

It is often said that having gone through any kind of suffering tends to makes you appreciate life more and live more in the present. I'm not sure how universal or long-lasting these effects really are.