The standard rumor at the time was that Rumsfeld, as chief of staff, had persuaded President Ford to appoint George H.W. Bush as director of Central Intelligence, assuming that that got rid of a potential competitor for the presidency.
“If you were a medieval scholar reading a book, you knew that there was a reasonable likelihood you'd never see that particular text again, and so a high premium was placed on remembering what you read. You couldn't just pull a book off the shelf to consult it for a quote or an idea.”