Mr. Stephen Sondheim recently came backstage after the final performance at the 92 Street Y Lyrics & Lyricists production of Wordplay, written and hosted by Ted Chapin, gracing us all with warmth and positivity. With due reverence and never taking his presence for granted, I greeted him with (and this is something of a running joke between us), “You were wonderful, most of the time.” To which he darted back, “I’ll give you notes later.”

I expect, hope for, and welcome those notes via email. I sang many songs in the concert—including the deceptively simple “Send in the Clowns” and the profoundly brief “Loving You”—that probably have a fine navigational instrument attached within his observing brain that sways left and right in infinitesimal reaction to a performer’s inflections and vocal tone. As God is in the details, imagine performing for God.

I loved being a part of the production, and seeing new circles of intimacy grow around his music...in spirals of devotion, effort, fear, and desire to excel. Everyone wanted to do well (and did!), and several there had not sung his songs and were thrilled to learn them. I found myself sharing this or that obsessive detail I’ve gleaned over two years of making my Sondheim Sublime album, previous tribute concerts, reading his amazing books, watching films and documentaries, and 15 years of performing his music, beginning when I played Dot in Sunday in the Park With George opposite Raúl Esparza at The Kennedy Center Sondheim Celebration in 2002. After productions of Passion, Do I Hear A Waltz?, and a recent Into The Woods with Alice Ripley, I now have so many references that I can, if asked, be a teacher (a word Sondheim elevates often, saying there is no greater thing to be).

Many experts were around, and I raced after any insights, especially from Ted Chapin, writer Jack Feldman—who co-hosted the evening—and the brilliant musical director Andy Einhorn. So over the week, everyone was inspired, further converted, and honored to meet him.

The set list was changing constantly, but one song of mine that was always included was the saucy “Miller’s Son” from A Little Night Music.

I shall marry the miller's son,
Pin my hat on a nice piece of property.
Friday nights, for a bit of fun,
We'll go dancing.
Meanwhile...

It's a wink and a wiggle and a giggle in the grass
And I'll trip the light fandango,
A pinch and a diddle in the middle of what passes by.
It's a very short road
From the pinch and the punch
To the paunch and the pouch
And the pension.
It's a very short road
To the ten thousandth lunch
And the belch and the grouch
And the sigh.
In the meanwhile,
There are mouths to be kissed
Before mouths to be fed,
And a lot in between
In the meanwhile.
And a girl ought to celebrate what passes by.

Backstage, Steve told us that he had a friend whose daughter was born on December 25. Steve was in her presence one day when her parents asked if her if she minded her birthday and Christmas colliding on the same day. She replied, “I want to celebrate everything!” And he clocked that outburst in his mind as a future lyric.

I love hearing about lyric origins, and I had spent the rehearsal process curious about another lyric from that sexy song. I was interested in tracking the origin of the phrase “trip the light fandango” in the first verse, as it always caught me up and I wondered, “What I am talking about?” I asked him, briefly and shyly, backstage if he had drawn it from the poet Milton, and he said he wasn’t sure it went back that far. There was other backstage conversation to be had and I didn’t speak further on the subject. He was so generously talking to our whole proud and beaming cast, gathered around him in an unforgettable, collegial circle, each attendee with a full—or empty—champagne glass in hand.

What I didn’t get to say to him was that I had been doing verbal archaeology on the “light fandango,” spending hours in my own secret rabbit hole, delighting in details and curios like a little girl getting lost in a museum after hours. And, as with all Sondheim archaeological digs, I always find treasures. Ultimately useless perhaps, but exploration itself has pleasures and action its own reward, a twist on Dot’s own logic in Sunday in the Park: “I chose and my world was shaken/ so what?/ The choice may have been mistaken/ the choosing was not.”

With a little help from the OED and a bookish friend, I found that “trip the light fantastic” indeed comes from John Milton’s L'Allegro, the study of the upbeat man, or Mirth, which is, the companion poem to Le Pensero, about the downbeat one, or Melancholy—both inspired, it's said, by two statues in Michaelangelo's Medici tombs. (I was art history honors at Yale, hard to conceal my interest in these matters.) The original phrase in Milton is:

Sport that wrinkled Care derives / And Laughter holding both his sides / Come, and trip it as you go / On the light fantastic toe

He was using “trip” not to mean pratfall, but “graciously.” And apparently Milton's line became an idiom, perfectly illustrated by Blake in his 18th-century watercolors of Milton's poems, where they really are tripping the light fantastic. As far as academics can tell, the first use of it in American pop music is in “Sidewalks of New York” by Lawlor and Blake in 1894: "Boys and girls together, me and Mamie O'Rourke/ tripped the light fantastic/ on the sidewalks of New York."

So when did it become (or why did Sondheim make it) “trip the light fandango”? Since he also has Petra “pitch the quick fantastic,” it seems quite, well, Miltonian, but where does “fandango” come from?

I don’t follow rock much (to my husband’s dismay), and Steve is firmly anti-rock (Laura Nyro an exception), but I have come to understand that a variant of the phrase became famous in the 1969 Procol Harum psychedelic song, "Whiter Shade Of Pale": “We skipped the light fandango/and did cart wheels round the floor.” (As I type this, my husband looks over my shoulder and sings every line.) In that case, “skipped” had changed meaning to tripped on LSD. (Aside: I have heard of James Lapine’s new LSD musical in development, and I'm intrigued.) But there are said to be—though they seem impossible to trace—even earlier versions of “light fandango” where it refers to a Spanish dance.

So which was Sondheim’s inspiration? I can't imagine he cared for the Procol Harum song, so have to assume it was already an idiom when he used it. Having both “the quick fantastic” and “the light fandango” is a nice turn. Or was it the old New York song? Or what?

I may never get my answer. Petra’s song is amazing, and I’ll be singing it again and again in coming weeks, from the Playbill cruise on the Rhône River to the Zedel in London in May, and onward. Isn’t that Blake image attached above just scrumptious? A rustle in the hay indeed. It’s also quite possible Petra was making a mistake—mixing all these references up—and all this is her illiterate pretension. No matter! Or maybe that’s the whole point! Fun to sing of Petra’s petticoats flying with so much else tripping along in mind.

Errico has Sondheim concerts in London May 6–8 at Live at Zédel, as well as Cry For Joy: Melissa Swings American Songs at Manhattan's Birdland June 3, with a five-piece band headed by Matt Baker.