Ah, falanghina, I thought I knew you.

It is true of wine that the more you learn, the less you know. So it was that in researching falanghina, an ancient grape that has been revived in recent decades in the Campania region of southern Italy, I learned that falanghina is actually two genetically distinct grapes, falanghina beneventana and falanghina flegrea.

But the two varieties are difficult to differentiate, according to a pair of essential books, “Wine Grapes” by Jancis Robinson, Julia Harding and José Vouillamoz, and “Native Wine Grapes of Italy” by Ian D’Agata, and are often but not always blended together in wines that go by the generic name falanghina. For what it’s worth, Mr. D’Agata suggests that the falanghina beneventana tends to be more floral and structured than the falanghina flegrea, which is generally more fruity.

While this may be of passing interest to consumers who simply want to know which bottles to buy for dinner, it illuminates the degree of uncertainty with which one must approach wine. What we think we know is often instead only what we believe. And what we believe is occasionally proved to be wrong.

As far as falanghina goes, generally, I have long believed it to be a source of highly pleasant wines with lively acidity and intriguing floral and mineral flavors. It can be a great value on restaurant wine lists. Maybe it doesn’t have the potential of fiano, another ancient grape of Campania, to make wines of depth, complexity and finesse. Nonetheless, what it does do, I’ve thought, it does well.