We are here by luck, not by right or by necessity. Rudimentary biology reveals how extreme the situation is. My existence depends on the birth of a particular organism that could have developed only from a particular sperm and egg, which in turn could have been produced only by the particular organisms that produced them, and so forth. In view of the typical sperm count, there was very little chance of my being born given the situation that obtained an hour before I was conceived, let alone a million years before … If you concentrate hard on the thought that you might never have been born – the distinct possibility of your eternal and complete absence from this world – I believe you too will find that this perfectly clear and straightforward truth produces a positively uncanny sensation. Thomas Nagel