If, before you die, you want to understand why you lived in the first place ...

The following is from Richard Dawkins' foreword to the 1993 edition of John Maynard Smith's 'The Theory of Evolution':

Darwin's theory of evolution by natural selection is the only workable explanation that has ever been proposed for the remarkable fact of our own existence, indeed the existence of all life wherever it may turn up in the universe.  It is the only known explanation for the rich diversity of animals, plants, fungi and bacteria; not just the leopards, kangaroos, Komodo dragons, dragonflies, corncrakes, coast redwood trees, whales, bats, albatrosses, mushrooms and bacilli that share our time, but the countless others - tyrannosaurs, ichthyosaurs, pterodactyls, armour-plated fishes, trilobites and giant sea scorpions - that we know only from fossils but which, in their own aeons, filled every cranny of the land and sea.  Natural selection is the only workable explanation for the beautiful and compelling illusion of 'design' that pervades every living body and every organ.  Knowledge of evolution may not be strictly useful in everyday commerce.  You can live a sort of life and die without ever hearing the name of Darwin.  But if, before you die, you want to understand why you lived in the first place, Darwinism is the one subject that you must study.  ...