Every autumn, as the leaves on my sycamore darken, the books on my nightstand tend to get a little darker, too. Summer books for the beach often give way to books about more serious topics. A vivid recent example is “Mortality,” by Christopher Hitchens, which sports a jacket as black as a Halloween cat. As my copy of “Mortality” migrated through the house last week, moving from bedside to coffee table to the armrest of my favorite chair, its dark-as-night dust jacket seemed right at home with the neighborhood decorations for All Hallow’s Eve. I think that happy coincidence would have amused Hitchens, who had a wry sense of gallows humor.

“Mortality,” as the title suggests, is Hitchens’ chronicle of his final days after being diagnosed with terminal cancer in 2010. Hitchens, a gadfly journalist and social commentator, was on a book tour when he fell ill with the sickness that would, by the next year, claim his life. Although its premise sounds depressing, “Mortality” is a book about death that, like so many other works of its kind, is really a book about life.

Hitchens was famous for a great number of things, but much of his celebrity stemmed from his role as an atheist and critic of organized religion. He counted practicing Christians and Jews among his friends, and although his diagnosis inspired gloating among some religious zealots, more tolerant believers tried to comfort Hitchens during his illness. That such friendships could grow across such a wide gulf in belief is a testament to the kinds of differences that can be bridged when people agree to disagree, even on such a profound matter as the question of God’s existence.

By comparison, the other divisions touching our country, such as the differences between political parties, seem much easier to reconcile — if we’re willing to recognize that tolerating beliefs beyond our own can be a strength, not a weakness. It’s an idea worth keeping in mind as Americans sweep up the confetti from a prolonged and partisan presidential campaign.

Surprising things can happen when people shake hands across their disagreements. Consider, for instance, the odd development of a regular churchgoer like me reading the decidedly nondevout Hitchens and finding my faith deepened by the experience.

As his friends help him navigate his final days, Hitchens writes in celebration of the kindnesses that arrive at his sickbed, offering observations that can touch readers regardless of their views on religion.

“My chief consolation in this year of living dyingly has been the presence of friends,” Hitchens writes shortly before his death. “I can’t eat or drink for pleasure anymore, so when they offer to come it’s only for the blessed chance to talk.” We stand near the doorstep of the holidays, annual celebrations meant to affirm our blessings. “Mortality” is a reminder that we don’t have to wait for such special occasions to acknowledge the many good things — and good people — that can touch a day and make it golden.