We cannot get adequate nutrients even from eating healthy foods, the authors argue, since modern processing reduces much of our food's nutritive value. Our biological defenses need to be enhanced in order to fight unnatural toxins from processing and pollution. Also, toxins aside, our bodies simply didn't evolve to live many decades beyond what the authors refer to as the child-rearing years. Government recommendations and much common medical practice don't take these factors into account. Ray & Terry aim to correct this.

Kurzweil's own story is instructive. I've seen him give an artificial intelligence technology demo - actually, "performance" would be a better term - and he certainly acts and looks fitter than most men his age. Now in his fifties, he has been for many years completely free of indications of the type 2 diabetes he was diagnosed with at 35. He attributes his good health in part to the dozens of supplements he takes each day, and the reader will be inclined to concur, but will at the same time clearly understand that Kurzweil has turned himself into a living experiment.

For most of us, it would be a full-time job - at least for a while - to undergo all the examinations and testing Kurzweil puts himself through. As well, authorial protestations aside, it would be expensive to buy all the supplements that thorough testing would indicate for any one of us. And, in addition to his own initiative, Kurzweil seems to be a sort of "special project" of his co-author, clearly an unusually curious and devoted doctor.

For those unfamiliar with Ray Kurzweil's work, I'll also mention that he happens to be a kind of super-genius. All the good health in the world might not enable most of us to maintain his kind of schedule and multiple careers and still tend to the painstakingly individualized health care we would need to get us safely to Bridge Two.

Still, we read travel books and watch TV shows about places we may never visit. We read fictions about adventures we'll never have and futures we won't live to see. There's nothing wrong, and much good, with reading about people who test the frontiers of health care. Some readers will be able to put into practice some, or even many, of this book's recommendations. Others will not. But any curious human will be likely to find the book something of a revelation.