I still regard adventure pretty much as a hobby to tell you the honest truth, and I think this approach to it keeps one refreshed almost. I think if you just regard adventure as a business, working becomes very boring as many other businesses can become. But even though adventure changed my life considerably, both in what I was doing and even economically, I’ve always regarded myself in a sense as a competent amateur.

They were blocked in their minds to do this because they thought, oh this is not done, we don’t do that in our field and you can’t do that, and I said: Why not?

I notice that if you have the door to your office closed, you get more work done today and tomorrow, and you are more productive than most. But 10 years later somehow you don't know quite know what problems are worth working on; all the hard work you do is sort of tangential in importance. He who works with the door open gets all kinds of interruptions, but he also occasionally gets clues as to what the world is and what might be important.

It’s how we are made as homo sapiens. We are biologically organized to cover distances on foot. That’s what we did for tens of thousands of years until we started to use horses, of course, until the mechanical age. And I would not call it “walking” because it’s not going out for a stroll or going out for a “power walk” or ambling in your city. It’s “traveling on foot.” You are reading the world, learning the essence of the world.

And now, weak, short of breath, my once-firm muscles melted away by cancer, I find my thoughts, increasingly, not on the supernatural or spiritual, but on what is meant by living a good and worthwhile life — achieving a sense of peace within oneself. I find my thoughts drifting to the Sabbath, the day of rest, the seventh day of the week, and perhaps the seventh day of one’s life as well, when one can feel that one’s work is done, and one may, in good conscience, rest.

It was this celestial splendor that suddenly made me realize how little time, how little life, I had left. My sense of the heavens’ beauty, of eternity, was inseparably mixed for me with a sense of transience — and death. ... I told my friends Kate and Allen, “I would like to see such a sky again when I am dying.” “We’ll wheel you outside,” they said.

I feel a sudden clear focus and perspective. There is no time for anything inessential. I must focus on myself, my work and my friends. I shall no longer look at “NewsHour” every night. I shall no longer pay any attention to politics or arguments about global warming. This is not indifference but detachment — I still care deeply about the Middle East, about global warming, about growing inequality, but these are no longer my business; they belong to the future. I rejoice when I meet gifted young people — even the one who biopsied and diagnosed my metastases. I feel the future is in good hands.

I cannot pretend I am without fear. But my predominant feeling is one of gratitude. I have loved and been loved; I have been given much and I have given something in return; I have read and traveled and thought and written. I have had an intercourse with the world, the special intercourse of writers and readers. Above all, I have been a sentient being, a thinking animal, on this beautiful planet, and that in itself has been an enormous privilege and adventure.

The first biography I read — I think the first scientific biography — was Madame Curie . And my mother, who was a surgeon, worked at the Marie Curie Hospital. She’d met Marie Curie, who was one of her great heroines. And reading the book, I think, was the first portrait of a scientist and the romance of a scientific life.

And I spent four years at a boarding school in the country, probably a rather abusive boarding school, and seeing very little of my parents, and that was a very bad time for me. A bad and almost a mad time. ... I think that some sort of trust, and ability for closeness, may have been compromised. And I think I’ve perhaps, to some extent, sort of kept a distance since that time, although this is not a distance I feel with my patients or my students.