How do you fathom the unfathomable?  “My mother is a supernatural being, beyond the reach of ordinary mortals”, says Stéphanie Argerich in Bloody Daughter, her revealing 2014 documentary about the complex relationship she has with pianist parents Martha Argerich and Stephen Kovacevich. The title is a comment of her father’s, not, as is often assumed, somehow related to her mother.

One of the greatest pianists of the last 50 years, and still playing at the age of 75, Martha Argerich is famously media shy. She doesn’t do interviews, she fell out of love with the recording studio in the 1980s, ditto with solo performances, preferring the camaraderie of chamber music or working with an orchestra. She has a reputation for cancelling, yet she’ll dep for a colleague, as she did last month for Maurizio Pollini, at the shortest of notice. To paraphrase Winston Churchill, like Russia, Argerich is a riddle wrapped in a mystery inside an enigma. Or is she?

Martha Argerich, Pianist Martha Argerich. Photo © Adriano Heitmann/Immagina, Deutsche Grammophon​ 

Like the Queen, we don’t expect her to do banal things like go to the toilet, use a mobile phone or...