When I wake up each morning, I am less likely to reflect that a new day has arrived than that yet another day has departed. What we unthinkingly call “the passage of time” tinges the first few minutes with apprehension. I am reaching the end of my sixties and, although the end is as invisible as it ever was, my probability of dying in a given year is many times greater than when, as a teenager, I first tried to imagine the extinction of my life, my world, and all those who had shared it with me. My human being is more begoing than becoming. I am somewhere between suppertime and midnight in my life’s day.

What’s more, the pace seems to be quickening. On each January 1 the number designating the year just past looks less used up than its predecessor. By the time 1960 had arrived, my 1959 was worn out and its replacement overdue. When 2011 was announced, I was still not used to 2010 and even 2009 and 2008 looked scarcely touched. It is hardly surprising that I sometimes feel — as I imagine you, reader, do when yet another day, another week, another summer, another year has melted away — as if I were being swept, log-like, towards a cataract dropping into oblivion.

This feeling of suppressed panic has prompted me to think systematically about time, perhaps in the hope that, by cultivating a special kind of attention to it, I might slow it down or (if the expectation of having such an impact on the universe was unrealistic) slow my own passage to oblivion. Of course, most thinking about time, especially in the last century or so, has been done by physicists. But if thinking about time is an indirect way of meditating on our mortality, then we need to focus on time as it is lived. This means rescuing time from the jaws of physics — challenging the increasingly prevalent assumption that physics has the last word on the nature of time.