The American minimalist painter Robert Ryman has donated a collection of 21 paintings to New York’s Dia Art Foundation, according to the New York Times.

Together with a work that the foundation already owns, the 22-piece group of works on view at the foundation’s Dia:Beacon now comprises the most comprehensive survey of Ryman’s work held by an American public institution. That’s a hallmark unlikely to change given the development of the artist’s market price.

The bequest—which has been on view at the upstate New York space since it opened in 2003—could be worth up to $420 million according to artnet’s Price Database, which indicates the artist’s record price currently stands $20.6 million.

Speaking on behalf of the artist, his son Cordy said his father waited for the institution to stabilize after the loss of key patrons and numerous abrupt leadership changes before bequeathing the works.

The newly acquired pieces fit neatly into the Dia Foundation’s existing permanent collection, which focuses on minimalist and post-minimalist art and includes works by Ryman’s contemporaries such as Dan Flavin, Sol LeWitt, Agnes Martin and Donald Judd.

Dia:Beacon. Photo: Bill Jacobson studio, New York, courtesy Dia Art Foundation, New York.

“Ryman is completely central to Dia’s mission,” director Jessica Morgan told the Times. “This is a culmination of almost 30 years of the foundation’s involvement with his work” she said, adding that she was always optimistic that the works would remain with the foundation.

Robert Storr, president of the Greenwich Collection which oversees Ryman’s work, said the constellation of the Dia’s Ryman holdings presents his work in the best possible conditions. “His paintings make the most sense when they’re experienced like this,” he said. “The space, the light, the fact that they can really be seen on their own terms are things that Bob has thought about very hard.”

In fact, the artist personally installed the works in a 2009 rehang to align with his vision for his work, and is the only remaining installation he put together himself.