(WSJ) - A FEW YEARS AFTER I embarked on a career as a wine critic, I found myself in the cellars of a fairly well-known Bordeaux producer. My wife and I were on holiday and I had surreptitiously scheduled an afternoon appointment at a château not far from Saint-Émilion. The only problem: The vigneron hadn't been told, and I hadn't told my wife. So, as he poured out his first barrel sample, I thought I'd better concentrate.

Lowering my nose into the tasting glass, I managed to detect a few telltale aromas: blackberry, red currant, vanilla and a hint of dark chocolate. It was enough. The vigneron's mood visibly improved and my spouse later admitted that it was the first time she actually believed that, when it came to wine, I knew what I was talking about.

Wine appreciation is fundamentally linked to smell. Much of what we taste in the glass—about 70%—is based on its bouquet. There are more than 1,000 different aroma molecules in wine and yet, outside the rarefied world of professional wine tasting, I suspect most drinkers can only detect a handful.

Our sense of smell is one of our most powerful senses. But unlike our eyes, which automatically recognize color, and our ears, which are attuned to detect sounds, our nose needs to be trained. What I had demonstrated in the cellars of Château Fonroque wasn't some sort of magic trick but an analysis based on concentration and olfactory memory. It isn't hard, anyone can do it. But it does take a little application and time. And as anyone who has sufficiently developed their sense of smell and learned the basics of a wine-tasting vocabulary will tell you, once mastered, wine will never taste the same again.