This dictionary has been compiled from extensive evidence of the quotations that are actually used in this way. The dictionary includes the commonest quotations which were found in a collection of more than 200,000 citations assembled by combing books, magazines, and newspapers. For example, our collections contained more than thirty examples each for Edward Heath’s “unacceptable face of capitalism” and Marshal McLuhan’s “The medium is the message,” so both these quotations had to be included.