I just bought this book, Clear and Simple as the Truth: Writing Classic Prose, by Mark Turner and Francis-Noël Thomas (Princeton, 1994), on the basis of this review by the late Denis Dutton. It is not a writing manual, but a description of a single prose style characterized by a particular relation between writer, subject-matter, and reader. The book does not say that this is the only valid style, but it is itself written in an approximation of classic style, with a "museum" of examples following.
Some differences between "classic style" as defined by T and T and conventional academic prose:
Academic prose contains much more argumentation, hedges, and self-conscious sign-posting. Classic prose simply asserts facts and judgments and is organized seamlessly. It appears unhurried and effortless, even when it might have cost a lot of effort on the part of the writer. The classic pose assumes a certain equality between writer and reader: both are competent, and the reader could reach the same conclusions when presented with the same evidence.
Clear and Simple does not concern itself with the surface accidents of good prose, grammar, usage, punctuation. It assumes that the "elements of style" are not such issues, but fundamental concepts concerning the relation between language and thought and between writer and reader. Change any of these suppositions, and the style too will change.
This is a brilliant and subtle book. Because it attempts to mimic the style it describes, it avoids arguing for the virtues of the style against any others, preferring to assert by example. It is lucid about the differences between "classic style" and other stylistic choices, the "plain style," the "romantic style," etc..
I highly recommend this book, not because I think everyone should emulate the classic style, but because the writers think so lucidly about style as a set of assumptions about knowledge and communication. You could use the book to learn to write classic style as your own chosen mode, or to refine whatever style you choose as your own.
I wonder if this book has had any repercussions in the world of composition and rhetoric.