THE BERKSHIRES: Whatever did happen to all of the firebrand 1970s freedom-now feminists who filled the covers of all the news magazines, won all those awards and made so much history? What happened when the photographers went away?

That is the plot of Sarah Treem’s The How and the Why, now running at the Elayne P. Bernstein Theatre at Shakespeare & Company in Lenox, Massachusetts. Her heroine is Zelda Kahn, a brilliant scientist whose “Grandmother Theory,” that women in ancient times continued to help their children and grandchildren well after their own reproductive years ended (and do so today). Now Zelda, in her late 60s, is confronted by a hot new lab rat scientist, Rachel Hardeman, who has an electric new theory on menstrual cycles that she thinks will make her famous, as famous as Zelda, who, she has just learned, is actually her biological mother. The unmarried Zelda gave up Rachel, now 28, for adoption because she believed that a child would get in the way of her soaring career. She has not seen her since then.

Rachel, whose adoptive parents both died and now is madly in love with fellow scientist Dean, meets with Zelda in order to somehow get the chance to read a science paper at the national conference whose board includes Zelda. At the same time, berates her for abandoning her all those years ago.

The confrontation in Treem’s extremely perceptive and marvelous new play is fiery and, at the same time, in an odd and unexpected way, comforting. Treem has drawn two in-depth, brilliant and very understandable characters in this two woman generational play and, at the same time, carried on the age old debate of woman’s place in the world.

At first, the argumentative and accusatory Rachel is thoroughly obnoxious and you hate her and everything she stands for. You feel sorry for good old Zelda, who never married and won all those awards and is a prestigious professor. As the play deepens, though, Treem takes away the antagonism of the two women and shows them for the admirable people they are beneath their tattered exteriors. It’s a tough journey to get there, though,

Rachel does talk Zelda into giving her the spot in the conference where she tried to trailblaze her new theory, sure that the crowd would stand and applaud her. It did not; the talk was a disaster. She was not only crushed by the talk, but her lover, Dean, suddenly left her. All she has now in the word is her biological mother, whom she hardly knows, and has been jousting with for an evening.

Zelda, on the other hand, is a woman of great mystery. She constantly thwarts Rachel’s attacks on her, backs off from every accusation and tries to explain that a lifetime of work in biology is more than enough for any women, that love and kids are not needed. As the night wears on, she questions that belief. Were there mystery men in her life? Who was really the father of Rachel? Can the hot shot Rachel really make it in the super competitive world of academe and science?

Treem explores a lot of themes in the -- at times -- lovely and -- at times -- scalding play. What did happen to all those feminists? Zelda’s life was full of triumphs and yet, at the same time, full of emotional pain. She did many things right, but a lot of things wrong. The people she thought would always support her ignored her. She admits at one point, fed up with the world, that a lot of feminists made big mistakes in their lives and always blamed the world for them, and not themselves and their bad decisions.

Hot headed Rachel, with a foul mouth that often brings waves of laughter, is absolutely certain that she can live without Dean, without men, without anything except her beloved theory which, in the end, turned out to be questionable, too.

What happens to the mother and daughter at the end? Do they finish that night as they began, bitter enemies, or somehow through all that emotional wrestling, come back together after 28 long and empty years?

The playwright (one of the writers for the hit Netflix television series House of Cards), has done a fine job with history in the drama. The reproductive theories in the play are real, taken from Natalie Angier’s book Woman: An Intimate Geography, about “grandmother” theorist Kristen Hawkes and the menstrual cycle researcher Margie Profet. She has also etched a fine, representative feminist in Zelda, a woman who like all the feminists of the 1970s, climbed many mountains in America, often at a great personal and emotional cost. They were true champions, but like all champions, they hurt a lot.

Treem has plenty of help in The How and the Why (that means how we were born and for what purpose). Director Nicole Ricciardi should be applauded for her deft work in making a two woman play a full and engaging night in the theater. You can see the director’s deft hand in all of the drama of the play. She gets sensational performances from Tod Randolph as the older Zelda and Bridget Saracino as the younger Rachel. The two gifted actresses give their characters love and anger and a great sense of fortitude. Their characters are, in a way, just like everybody else and their problems, while unique, are, somehow, the same problems we all have in one way or another.

PRODUCTION: The play is produced by Shakespeare & Company. Set Design: Patrick Brennan, Costumes: Deborah Brothers, Lighting: James W. Bilnoski, Sound: Alexander Sovronsky. The play is directed by Nicole Ricciardi. It runs through July 26