Just 150 years ago, Dostoevsky sent his publisher the first chapters of what was to become his strangest novel. As countless puzzled critics have observed, The Idiot violates every critical norm and yet somehow manages to achieve real greatness. Joseph Frank, the author of the definitive biography of Dostoevsky and one of his most astute critics, observed that it is easy enough to enumerate shortcomings but “more difficult to explain why the novel triumphs so effortlessly over all the inconsistencies and awkwardnesses of its structure.” The Idiot brings to mind the old saw about how, according to the laws of physics, bumblebees should be unable to fly, but bumblebees, not knowing physics, go on flying anyway.

Picture Dostoevsky in 1867. With his bride, Anna Grigorievna, he resided abroad, not for pleasure but to...