Â© Oxford University Press 2007. All rights reserved. The publication of Darwin's On the Origin of Species in 1859 led to considerable psychological insecurity for many people over the place of humanity in the 'scale' of nature, and over our relationship to other creatures and to God. This chapter focuses on some links between ancient and modern expressions of such worries. It argues that the Epicurean theory of the origin of species may come closer to modern evolutionary theories than we have realized, and may quite naturally share many of the problems that modern evolutionary theories face.