One of the more embarrassing and self-indulgent challenges of our time is the task of relearning how to concentrate. The past decade has seen an unparalleled assault on our capacity to fix our minds steadily on anything. To sit still and think, without succumbing to an anxious reach for a machine, has become almost impossible.

We are continuously challenged to discover new works of culture—and, in the process, we don’t allow any one of them to assume a weight in our minds. We leave a movie theater vowing to reconsider our lives in the light of a film’s values. Yet by the following evening, our experience is well on the way to dissolution, like so much of what once impressed us: the ruins of Ephesus, the view from Mount Sinai, the feelings after finishing Tolstoy’s Death of Ivan Ilyich.

The need to diet, which we know so well in relation to food, and which runs so contrary to our natural impulses, should be brought to bear on what we now have to relearn in relation to knowledge, people, and ideas. Our minds, no less than our bodies, require periods of fasting.