I'd been referring to Sophie and Michael Coe's The True History of Chocolate for years before I finally got my own copy. Our library is only six blocks away, and open seven days a week. But the day came when the precious tome was checked out and I had some facts to check for a column. I called my husband, who was out running errands anyway, and asked him if he could please pick me up a copy -- any good bookstore would be sure to have it in stock.

He's used to adding chocolate-related stops to any drive. But he had a harder time than either of us anticipated finding a copy. He finally lucked into one at the third bookstore he tried. The clerk told him that the book was about to come out in a new edition.

I was intrigued -- and very glad I'd gotten my mitts on a copy of the first edition. I'd certainly buy the new one when it was available. If there were significant differences between the two, I wanted to have both books. If it was just a case of a new introduction or cover art, I'd probably bring the new edition back to the store.

The cover art to the second edition is a little different. And the new introduction is the old one plus a paragraph. But that paragraph guided me to what was different about the new edition.

Before going any further, I should say that the Coes' True History of Chocolate is the ultimate work in the field. It manages to be at once utterly comprehensive and accessible -- no mean feat for a book that covers hundreds of years of history and dives into botany, literature, and medicine, all without breaking a sweat. Part of the reason this book is so enjoyable is that the writers themselves seem to be having such a good time. It doesn't read like a work of intensive, grueling research; it comes across as a story they couldn't wait to tell.

So what's the difference between the first edition and the second?

I had mixed feelings on seeing that neither the table of contents nor the page count had altered in the slightest. Part of me would have enjoyed a new book that was really new; but anyone at all familiar with the first edition knows that a work so meticulously researched and skillfully laid out could only be harmed by a serious alteration.

The prose has been tightened up slightly throughout. Paragraphs that were once separate have quietly melted together.

It's difficult for this layperson to assess whether the first significant changes are worth the purchase of a new edition. In the first chapter of the original, the Coes go into some detail about what is apparently a much-debated topic: the question of whether or not "wild" cacao trees have been found in Mesoamerica, and where and when it was domesticated. In the second edition, the same topic is treated far more briskly and decisively.

The discussion of the chemical makeup of chocolate is also stronger and more to the point. In the previous edition, the Coes sound almost defensive at times. "Before we go into the details about caffeine," they say cautiously, "we should consider the fact that the studies showing the toxic effects of caffeine are made with the pure compound, a substance most of us will never see." Reading this, and the paragraphs following on the same subject, one would think that caffeine had been condemned as a positively toxic substance -- especially since we hear every possible side effect, some of them positively alarming.

The new edition handles the subject far more deftly. Caffeine is one of the alkaloids present in chocolate. A large bar of dark can have about as much caffeine as a cup of "American-style coffee." That's it. Theobromine, caffeine's chemical cousin, is discussed in more detail than previously. Also new to this edition, many ideas about chocolate's possible powers -- does it cause acne? will its antioxidants cure or prevent certain illnesses -- are touched upon.

The history of cacao's earliest cultivators and consumers is updated, as more archaeological information has come to light. The first edition's brief section on "The Olmec" is now a more detailed "The Olmecs and Their Predecessors." A couple of pages of non-chocolate-related meandering have been neatly cut out, replaced with information that is lively but to the point. More facts about the place chocolate held in Maya culture have been woven into the text.

I was deeply relieved that the second edition was as readable and, yes, as generously illustrated as the previous one. The True History of Chocolate is a beautiful work in every way, as tempting as your favorite bar of its subject matter. You pick it up thinking that you'll just have a nibble; but it's impossible to resist devouring the whole thing.