Warren Buffett shook the investment world on Saturday with four words: "The time has arrived." At 94, Buffett's pronouncement that he step back from CEO duties — which he will recommend to the board in a meeting set for Sunday — is less a shock than a matter of necessity.

Warren Buffett shared big news at the Berkshire Hathaway shareholders meeting yesterday: His plan to step aside as CEO later this year in favor of his longtime heir apparent, Greg Abel. If the announcement was huge, the timing was even more masterful.

One person who is more familiar with Buffett's life than most is Alice Schroeder, a journalist who wrote the 2008 bestselling biography of Buffett, "The Snowball: Warren Buffett and the Business of Life,