Everyone knows Mama Rose’s first line in 1959’s “Gypsy.” It’s “Count four before you start, Louise!” Or at least it was. But one day in rehearsal Ethel Merman crossed it out for the line everybody now knows: “Sing out, Louise!”

That nugget is among the discoveries in the Merman memorabilia collected by Tony Cointreau, an heir to the liqueur family. Cointreau considers Merman one of his “other mothers,” alongside Lee Lehman, wife of former Lehman Bros. topper Robert Lehman, and, of all people, Mother Teresa, with whom the former singer volunteered at orphanages in India. He chronicles his life with all three in his new memoir, “Ethel Merman, Mother Teresa … and Me.” Among the showbiz tidbits is this memory of a revealing backstage moment at “Gypsy.”

— Gordon Cox

“Knowing that Miss Merman was going through a difficult time with her divorce, (her daughter) Little Ethel and I decided to go to the theater at the end of her mother’s show.

We arrived at the Broadway Theater in time for the curtain calls. Miss Merman did not know we were there and was waiting in the wings to take her final bows. She was looking down at the floor, marking time while the rest of the cast went on stage. To my 18-year-old eyes, she looked like the saddest woman I had ever seen.

But as soon as Miss Merman’s time came to step out on that stage, I saw the most remarkable transformation. The moment the lights hit her, she somehow made them seem a little brighter than they had been for everyone else. It was as though someone had turned on a switch and released a power that could overwhelm and thrill you with its laser-like beam. The entire theater was electrified by a force of nature called Merman. … That evening, not only was I privy to the private moment of a very public human being in pain, but I was also inspired by a glimpse of true theater magic in action.”