We tend to think that everything important comes from the centre: from big cities, from established orthodoxies in the sciences and the arts, from the Establishment in all its forms. We think this because the centre tells us it is so, but it's a lie. It is only at the edges that we think, innovate and thrive.

This book travels to the far frontiers of the planet, and of human culture and consciousness; to the edges of continents, of evolution, of artistic and political movements, and of life itself: from a rocky precipice in the Peloponnese where the first human set foot in Europe to an ancient Egyptian temple where monotheism was invented; from St Francis, kissing lepers' sores to the giant bird-eating mice of St Kilda.

Why do we stare at sunsets? Why do we celebrate birthdays and grieve for those who are gone? Why do all adventures begin when we leave and get lost? Who has the better view of reality - the Government or the dispossessed? And what happens when we live with the knowledge that we're all teetering on the edge of the dark?