Of course, nothing can be said to argue that people are morally obliged to accept this ethic, for to do so would be inconsistent with the ideas that inspired it in the first place. It is an ethic that will be adopted – if at all – by those who find a certain stark beauty in kindness without reward, joy without purpose, and progress without lasting achievement.
(p. 308) - Darwin, God and the Meaning of Life: How Evolutionary Theory Undermines Everything You Think You Know (2010)