In 1995, Mark Silen was playing around with simple math and working with calendars when he stumbled upon something so amazing that he began to question nearly everything he had ever been taught. In "The Perfect Time: The Universal Calendar, " Silen shares the results of his research into one of the biggest coincidences in history-that man could have potentially missed the perfect measurement of time by one day. Never in a million years did Silen think that seven numbers-two easy addition equations and six simple multiplication equations-would apply to so many disciplines, but as he began to...