Celtic crosses, Celtic love knot jewelry, Celtic dancing, Celtic music . . . it’s an industry. Since my own choir, the Cherry Creek Chorale, does a Celtic-themed concert every other year, I wanted to find out more about the history of this term. Turns out that, as is usual when you try to reconstruct the past, especially the ancient past, it ain’t all that easy to nail things down. We’re used to thinking in terms of clear-cut events and eras when we look at history, but those divisions are often more for the sake of convenience than reflections of actual reality.