A good book review — and by good I mean no more than one which appears in the London Review of Books or Times Literary Supplement — might be two parts a discussion of the actual book, its prose, its subject, its lessons, and eight parts a discussion of whatever the book reviewer happens to want to discuss, especially and preferably any book not under review.
In-fact, a scale can be drawn from worst book review to best, with those at the former end treating the reviewed book as isolated subject and those at the latter only mentioning the reviewed book in conversation with a litany of others, which, as voluble dinner guests, might prompt an invested ear to remark, suddenly, “Wait, who’s hosting this again?” Or as a too-hungry shopper visits the store for one item and only realizes upon returning home and packing the groceries away that the one item has not been purchased.
Those at the former end — the bad reviews — are recognizable as the book reports of middle and high school, and maybe university. They quote the reviewed book at length, and their references all come from it. But the latter end consists of treating every book as being in a dialogue with anything and everything the book reviewer can reasonably ventriloquize. And the more interlocutors, the better. (I do not mix metaphors here: every book reviewer is having a multiple-personality conversation with himself; though he conflates his personalities as historical persons, stories, events, etc.)
It follows from this that a master book reviewer should be so widely read as to write a book review which avoids discussing the book under review entirely. Such, in one sentence, is the ambition of high-culture. Culture, in-fact, is only the measure of one’s ability to change the subject.
I am not well-read enough — yet — to write a good book review. I will thus content myself with bad ones for the next few years. The first among which is coming very soon. Can’t wait.