But in the weeks after I learned that the breast cancer I have been in treatment for over the past year had spread to my bones — breaking my spine and becoming incurable and most likely fatal — finding the perfect living-room couch has begun to feel like the most important thing I’ve ever done.

This is obviously not how I wanted things to turn out, but my wife and I have no regrets; we did everything I could to maximize my odds. And we want to thank everyone who has so graciously helped us. The really weird part of all this is that I'm not depressed. I'm not in denial (I assure you, I am fully aware of what is going to happen), nor am I whistling in the dark, but after having felt crappy and sick for 11 months, to finally be fully healthy again is so exhilarating that it's a wonderful emotional buoy. So I am going to enjoy each day very fully, and play hard with my kids until I can't.

Every 90 days I lie in a whirling CT machine, dye coursing through my veins, and the doctors look to see whether the tumors in my liver are growing. If they are not, the doctors smile and schedule another scan. The rhythm has been the same since my doctors told me I had stage IV colon cancer two and a half years ago. I live for three months, take a deep breath and hope to start over again. I will probably do this for the rest of my life. Whatever that means.

I began to realize that coming face to face with my own mortality, in a sense, had changed both nothing and everything. Before my cancer was diagnosed, I knew that someday I would die, but I didn’t know when. After the diagnosis, I knew that someday I would die, but I didn’t know when. But now I knew it acutely. The problem wasn’t really a scientific one. The fact of death is unsettling. Yet there is no other way to live.

It could really have an impact if I get it right. Something that will get the next generation to see there is a way to think about politics that is not just the way we've been habituated to do it. I care about that and I think I can do it.

So it seems to be my responsibility, particularly to my children, also to my wife and friends, is not to be Pollyanna and pretend everything's okay no one would take me seriously if I said that but it's to be as present in their lives now as I can be so that in years to come, they don't feel either guilty or bad at my having been left out of their lives, that they feel still a very strong not a memory of particular actions but a memory of a complete family rather than a broken one. That seems to be something I can do or try to do.

I think the only life experience that I have to offer out of this is something we all know in the abstract but don't experience in practice very much. That is that you can survive an awful lot of bad stuff, so long as your mind is intact. I'm afraid that's the only life experience I have to offer.

I was forced to think very hard about what it meant to be me, what it means to be a person who is only a brain. Pascal's 'thinking reed' really does capture it, because I'm just a bunch of dead muscles thinking.

During the day I can at least request a scratch, an adjustment, a drink, or simply a gratuitous re-placement of my limbs—since enforced stillness for hours on end is not only physically uncomfortable but psychologically close to intolerable. It is not as though you lose the desire to stretch, to bend, to stand or lie or run or even exercise. But when the urge comes over you there is nothing—nothing—that you can do except seek some tiny substitute or else find a way to suppress the thought and the accompanying muscle memory.

I don't believe in an afterlife. I don't believe in a single or multiple godhead. I respect people who do, but I don't believe it myself. But there's a big but which enters in here. I am much more conscious than I ever was, for obvious reasons, of what it will mean to people left behind once I'm dead. It won't mean anything for me. But it will mean a lot to them. ... So in one curious way I've come to believe in the afterlife as a place where I still have moral responsibilities, just as I do in this life except that I can only exercise them before I get there. Once I get there, it'll be too late.