Of all literary genres, the essay is perhaps the best known and most widely despised. This is probably because few people reach the end of their education without having been forced to write essays upon subjects of no interest whatever to them, and of precious little interest to their teachers either. For a long time after I left school the word “essay” connoted for me the instruction to compare and contrast, at quite unnatural length and for purposes completely opaque, the characters of Banquo and Macduff. It was a long time before I wanted to read or write an essay again.

But brevity is the soul of wit, and there is often truer intellect in the distillation needed in the writing of an essay than in the compilation of every known or discoverable fact about the subject of a biography. It is better that a reader should wish an essay were longer than that a biography were shorter. In good writing, what is left...