A new detail about the closeness of current Apple CEO Tim Cook and the late Steve Jobs has emerged in an excerpt from the forthcoming book Becoming Steve Jobs. In it, as Fast Company reports, there is a story about Cook being so distraught toward the end of Jobs' decline in health that he went to get his blood tested to determine if he might have the same rare blood type as Jobs, and if a partial liver donation might have been feasible. It turned out that it was.

When Cook went to Jobs' house to tell him the good news, Jobs immediately refused the offer.

"He cut me off at the legs, almost before the words were out of my mouth," said Cook. "'No,' he said. 'I'll never let you do that. I'll never do that.' Somebody that’s selfish doesn’t reply like that. I mean, here’s a guy, he’s dying, he’s very close to death because of his liver issue, and here’s someone healthy offering a way out. I said, ‘Steve, I’m perfectly healthy, I’ve been checked out. Here’s the medical report. I can do this and I’m not putting myself at risk, I’ll be fine.’ And he doesn’t think about it. It was not, ‘Are you sure you want to do this?’ It was not, ‘I’ll think about it.’ It was not, ‘Oh, the condition I’m in . . .’ It was, ‘No, I’m not doing that!’ He kind of popped up in bed and said that. And this was during a time when things were just terrible. Steve only yelled at me four or five times during the 13 years I knew him, and this was one of them."

The book was written by veteran tech reporter Brent Schlender and Fast Company executive editor Rick Tetzeli, and Fast Company will be giving an exclusive preview of the book in its April issue.

Becoming Steve Jobs comes out March 24.

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