Celebrity sex therapist Dr. Ruth Westheimer turned 93 last weekend, and after decades on television and in the public eye, it is still a thrill to hear her, in her German /Swiss /Hebrew/ French/ American accented English, telling men to love their penises.

It’s even as thrilling if the voice is that of the actress Tovah Feldshuh, now starring in “Becoming Dr. Ruth” at Bay Street Theater in Sag Harbor.

Having performed as iconic, historic figures, Israeli Prime Minister Golda Meir and Justice Ruth Bader Ginsburg, the role feels like a no brainer to Tovah Feldshuh, who visited Dr. Ruth four times in her tchotchke filled Upper West Side apartment, to perfect her subject’s movements: her way of climbing to get things off high shelves, and manner of answering the telephone.

The premise of Mark St. Germain’s play being, Dr. Ruth is leaving her apartment, purging possessions but also taking a trip down memory’s darkest lane to limn her journey, nee Karola Seigel in Frankfurt, orphaned at 10, sent to Switzerland on a Kindertransport, handling firearms as a sniper in the Haganah during Israel’s war of independence, studying at the Sorbonne, 3 husbands, 2 children, 4 grandkids, a lifetime of memories to pack and unpack.

“This is not a play about packing,” insisted Tovah Feldshuh in a Zoom interview just prior to the play’s Bay Street opening. “It’s about how going over your possessions sparks memories.”

“Dr. Ruth has something vital in common with Golda Meir and RBG: These women created the scripts of their own lives. There’s an expression in Hebrew: Tikkun olam. Changing the world. My tikkun is transforming myself into other characters, so that the audience can transform.”

She continued: “Dr. Ruth changed the world: she brought sex from the bedroom to the dining room and living room. She taught everyone to be responsible for their own orgasm. Her biggest tikkun was bringing sex ed to the world on radio and television. And that’s connected to the love in her first years living with her parents and grandmother. The sexual aspect of human relationships brought back the warmth of home.

“Most challenging part artistically is keeping in her vocal melody of how Ruth speaks constant but not repetitive. The most challenging psychologically part where she is looking for information about her parents’ deaths. When the Soviets liberated Auschwitz, they found survivors—her family not among them. The Germans were meticulous record keepers, and yet the record stops. Documents say Murdered for her Father. Next to her mother’s name: Disappeared.

“Despite that, she’s enough of an optimist, even the ends of her sentences go up. She’s thrilled to have a seamless relationship with me. She stays away from people with negative energy.”

On opening night, which was also Bay Street’s return to live audiences, the theater was at one third capacity as per COVID regulations and the mood was celebratory, with Dr. Ruth in attendance. Taking the stage with Tovah, in twinned outfits, black pants and shoes, rosy loose-fitting shirt, down to the necklace Tovah had made to become Dr. Ruth, who, in turn, exulted in the way Tovah brought her story to life. She wanted everyone to know the history, especially in a time of increased anti-Semitism and Holocaust denial.

For Tovah Feldshuh, being Dr. Ruth, is the latest in a stellar career. In her newly published memoir, “Lillyville,” named for her mother Lillian, she describes growing up in Scarsdale. Filling Dr. Ruth’s giant shoes, as she had, playing strong historic women Israeli Prime Minister Golda Meir and Justice Ruth Bader Ginsburg, is no feat compared to a lifelong effort to please Lilly.