On Thursday night in New York, at an auction house on the Upper East Side of Manhattan, Sotheby’s, the centuries-old British art broker, sold a painting by the late Mark Rothko for US$26.4 million or just under $35 million Canadian. That’s on the low end for a classic Rothko canvas these days. The painting — red and orange with a single bar of hazy blue — isn’t huge; it’s about five feet tall. And it’s never been owned by a major museum.

The Rothkos that have shattered art world records, paintings like the one that sold for an astonishing $115 million in 2012, tend to be much bigger. They tend to occupy the entire eye and overwhelm. They tend, in other words, to look a lot like the Rothko that’s sitting today in a storage room in Toronto, tucked away with the oddities and the other hidden works in the massive, mostly unseen collection of the Art Gallery of Ontario.

The AGO’s Rothko, painted in 1962, hasn’t been on display in Toronto in years. It’s a decision that baffles the artist’s son. “I think (it) is easily one of the 20 greatest Rothkos ever painted. Maybe higher,” Christopher Rothko said in New York last week. “I’ve been to the AGO four times and it has never been on display. And I just don’t get it. It’s not like they have other Rothkos that are hanging. It’s not like they are hanging exclusively Canadian art.”

Christopher Rothko was six years old when his father died, by suicide, in 1970. He is a psychologist by training, but is also, along with his sister Kate Rothko Prizel, the guardian of and a global champion for his father’s work. He organizes exhibitions. He gives talks. He even wrote a book about the work, and his relationship to it, that came out in 2015.

Christopher Rothko believes the AGO’s canvas, No.1, White and Red, 1962, is indicative of the absolute best of what made his father one of the most revered American artists of the 20th century. “I think the emotional impact and also the compositional purity of that painting are almost second to none,” he said. “So this is a plea to get that painting out of storage — or, if not, I’ll swap with them.”