In an appendix to his latest book on English usage, Bill Bryson lists 45 reference works for writers. He could have listed a hundred more, and still not exhausted the field. If professional writers err – and we err all the time – it is not for lack of authoritative guidance.

Bryson’s most recent contribution to the library is “Bryson’s Dictionary of Troublesome Words, a Writer’s Guide to Getting It Right.” It is published by Broadway Books, New York, a bargain at $19.95. In his introduction, Bryson sensibly addresses the whole idea of “authoritative” guidance. He says:

“One of the abiding glories of English is that it has no governing authority, no group of august worthies empowered to decree how words may be spelled and deployed. We are a messy democracy, and all the more delightful for it. We spell ‘eight’ as we do not because that makes sense, but because that is the way we like to spell it.

“When we tire of a meaning or usage or spelling – when we decide, for example, that ‘masque’ would be niftier as ‘mask’ – we change it, not by fiat but by consensus. The result is a language that is wonderfully fluid and accommodating, but also complex, undirected and often puzzling – in a word, troublesome.”

Up to a point, English is indeed anarchical. As Bryson says, if we choose to say “between you and I,” “we are free to say it and write it. The phrase is perfectly clear. It cannot be misunderstood. If we abuse such words as ‘replica,’ ‘fulsome’ and ‘decimate,’ no one will call the cops. But there is a point at which order takes over. It becomes ‘wrong’ to spell ‘accommodate’ with one ‘m.’ So useful a word as ‘ain’t’ becomes ‘nonstandard.’ Our speech betrays us.”

The process of reaching a consensus on “good English” has its mystic elements. Not long ago a reader asked for a ruling on the pronunciation of “short-lived.” Questions of pronunciation are off my beat, but out of curiosity I checked. Three of my everyday dictionaries say the long “i,” as in “ivy” or “item,” is the more popular choice. Three say the nod goes to the short “i,” as in “livid.”

Bryson covers all the usual questions of usage, such as “less” and “fewer,” but he covers most of them with unusual clarity. He bogs down, as all of us do, in explaining the distinction between “that” clauses and “which” clauses. He apologizes: To learn these distinctions, “it is necessary to understand restrictive and nonrestrictive clauses,” and this is “not anyone’s idea of a good time.”

Right on! On this cosmic matter, I can do no better than Bryson. My own rule is derived from the discipline of a gentlewoman of Virginia, a good Episcopalian, who annually made a Lenten pledge. She would not have a drink during Lent “unless I really need one.” So be it with “which.” Use it only when you really need it.

Browsing through Bryson is a writer’s stroll in a park. I had never thought of a distinction between “to spit” and “to expectorate,” but here it is: “To spit is to expel saliva; to expectorate is to dredge up and expel phlegm from the lungs.” Pay attention; this question will be on the quiz.

Bryson began his career as a copy editor, a magpie craft. He fills his nest with beads. It’s Magdalen at Oxford, Magdalene at Cambridge. Oxford has a Queen’s College, Cambridge a Queens’ College. It is “numskull,” not “numbskull.” On such gruel do copy editors happily feed.

James Kilpatrick is a syndicated columnist.