As the Lyndon Johnson biographer prepares to release his fourth volume examining the former president, a look at how Caro came to spend “36 years and 3388 pages” on LBJ:

“Johnson, who all along predicted an early end for himself, died at 64. Caro is already 76, in excellent health after a scary bout with pancreatitis in 2004. He says that the reason ‘The Passage of Power’ took so long is that he was at the same time researching the rest of the story, and that he can wrap it all up, with reasonable dispatch, in just one more volume. That’s what he said the last time, after finishing ‘Master of the Senate.’ (He also thought he could finish ‘The Power Broker’ in nine months or so. It took him seven years, during which he and his wife, Ina, went broke.) Robert Gottlieb, who signed up Caro to do ‘The Years of Lyndon Johnson’ when he was editor in chief of Knopf, has continued to edit all of Caro’s books, even after officially leaving the company (he also excerpted Volume 2 at The New Yorker when he was editor in chief there). Not long ago he said he told Caro: ‘Let’s look at this situation actuarially. I’m now 80, and you are 75. The actuarial odds are that if you take however many more years you’re going to take, I’m not going to be here.’ Gottlieb added, ‘The truth is, Bob doesn’t really need me, but he thinks he does.’”