Recently, I received an email from a good friend asking me to explain the grammar surrounding the word "but." On the surface, his question was easy-peasy: Is it okay to start a sentence with "but"?

But let me begin with two disclaimers:

First, as a former newspaper writer and editor, I have always claimed the journalist's exemption from grammar. That is, readability trumps rules. Every time. (See, that last sentence didn't even have a verb. Oh, Sister Mary Rosa would be so cross with me!)

Second, although I view myself as a writing expert and a darn good editor, I have never ever claimed to be a grammar expert. I know the basics, of course, but diagramming sentences gives me hives and I still have to think really hard about who versus whom. So, rest assured I don't intend to write an Agony Aunt [] column for the grammatically conflicted. It's just not my strength.

Still, I believe the "but" question raises an issue that's more interesting than it looks. So here are my thoughts:

1) If you want to break rules, know which ones you're breaking and why. Have a purpose.

2) Worry most about whether your readers will understand your writing. Grammar is a bit like courtesy -- it doesn't exist for its own sake -- instead, it's meant to make life easier and more pleasant. If you force your readers to go through your sentences more than once to figure out what you mean, then you're going to annoy them. The rules of grammar -- used as guidelines, not a straightjacket -- will keep your readers happy and help you communicate more effectively.

3) Equip yourself with at least one good reference book that will help answer your grammar questions. Like many others, I think the ne plus ultra is Fowler's Modern English Usage, edited by R.W. Burchfield. (If you buy "used," be sure to hold out for the 3rd edition which is easier to read.) I also highly recommend the marvellous Sin & Syntax: How to Craft Wickedly Effective Prose by Constance Hale.

Finally, to return to the matter at hand, there is actually nothing wrong with beginning a sentence with "but."

Says Fowler: "The widespread public belief that But should not be used at the beginning of a sentence seems to be unshakeable. Yet it has no foundation."

Says Constance Hale: "A-student types who memorized everything their English teachers said insist that coordinating conjunctions [such as but, and, or] cannot begin sentences. If editors ever try to feed you such wrongheadedness, throw these gems their way: And God said, Let there be light; and there was light. (Courtesy, the Old Testament.) Man is the only animal that blushes. Or needs to. (Courtesy, Mark Twain.) And after all the weather was ideal. They could not have had a more perfect day for a garden-party if they had ordered it. (Courtesy Katherine Mansfield.)

Take that, Sister Mary Rosa!