Dear X: You have been much on my mind, I’m terribly sorry I couldn’t make the birthday party, but it would have involved getting my head around another event in order to be present to you and Y, and I just didn’t think I would manage it in time. I didn’t do anything to “replace,” the situation, I think I just went home, praying that the work I have to get done got done, and I was free to have a drink with you…some time. But that time will come and everything will be in rightness again, and you will see how much I care about you, and how many times I think of how I met you, with your father, who you just learned was your father, and his immense pride in you, and how amazing it was, to see the physical similarities. I never asked why this was all kept a secret — every mother has her reasons — and I don’t think I would even ask you now had I not just watched Sarah Polley’s utterly extraordinary documentary about her late mother, Diane, a sometimes actress who suffered a devastating loss after her first marriage went awry: she lost custody of her first two children, who were raised by their father. After she fell in love with, and married Sarah Polley’s father, Michael, a romantic looking, very good British-born amateur actor whose shyness prevented him from living life on the stage (he became an insurance salesman) Diane had three children with him, Sarah being the last. Diane died, eventually, of cancer. It was revealed after her death that Sarah’s father wasn’t her biological father, that Sarah was the product of a love affair Diane had had when she was in rep, in Montreal (the Polleys lived in Toronto) with a young man named Harry, a shy filmmaker who was besotted by Diane’s presence on and off the stage. Diane was just over forty when she learned she was pregnant, and thought she would terminate the pregnancy for fear of a damaged child, but, on her way to the abortionist, she changed her mind, and Sarah was born, without whose critical, loving eye, we would not be watching the movie we we’re watching. All that said, Polley isn’t so much interested in chronology as a series of questions — proposals? — about the nature of truth, and the truth and imagination secrets can and do feed. As is often the case with children who feel they’ve been left, Sarah’s eldest brother and sister have different reactions to their mother’s affair; Sarah’s sister is besotted by her cast out Mum; she’s grateful that Diane was eventually loved, while her brother is angered anew by what he perceives as Diane’s recklessness; at the very least, he says, Diane’s pregnancy was a cautionary tale about how you should use birth control, particularly if you’re having an affair. (One gets the sense that this young man felt his mother left him three times, not only after her first marriage dissolved, but when she started a new family, and then died.) Polley let’s all her siblings and both fathers have their say — indeed, she is at pains to let them write their own familial tales; her siblings beautiful faces — they all have Diane’s eyes — are alternately and variously wide with humor and anger and tears as they talk about this ultimately unknown quantity: Mum. And it’s a measure of Polley’s power as a filmmaker that by allowing her “witnesses,” to have their say, she gets what she needs: a movie about layering, the truth dressed up as fiction, or fiction dressed up as the truth. It’s very odd, but it didn’t occur to me until the film was nearly over that the figures in the home movies were actors; they bore such an extraordinary emotional resemblance to the real life characters that the “real” people were discussing on screen, and off. I was so wrapped up in the various revelations–and the revelation that comes at the end of the piece — I almost forgot the various levels Polley was working on as a filmmaker. She’s very interested in the art that goes into artifice. (The opening of the movie in particular plays, through the use of ingenious camera angles and voice, with perspective in an intellectually and visually satisfying way, thus raising the stakes on the film’s various themes, and so on.) Polley was raised amidst fakery. The Dad who raised her was an actor. The Dad who is her biological father was a filmmaker. Diane performed. All of these elements went into Sarah Polley performing and directing — I very much liked her Alice Munro adaptation, 2006′s “Away From Her,” starring Julie Christie, another film about things not being what they seem — but how much of Polley the actress and director was nurture, and how much was destiny? As this film goes along, you see, in Diane’s “fake” face, and in the faces of both her lovers, a certain reluctance about performing (Polley films the mother who’s performing her mother through lots of doors, and as she’s putting on a coat, or walking away from the camera) or achieving greatly in the film world, that Polley cracks open with the clarity of her ambivalence: she would be seen, but she wanted to control it. That’s where her Diane DNA kicks in. Diane wanted the world to know who she was, even as she removed herself from it, performing the greatest role their is: mother. I can’t imagine what Polley went through to bring us this story, but how marvelous is it that Michael and Harry are there to largely not say what their relationship was to the largely unknowable woman who haunts the movie screens in their respective minds? This is the kind of filmmaking and writing that interests me: art that doesn’t pretend to objectivity, and so gets at a greater truth, beginning with how the women of Diane’s generation didn’t talk about their personal history and dreams so much as they kept moving ahead, hoping that they could keep skipping over their traces until the hard work of responsibility and romance paid off, and something like a better hope came along.