Damien Hirst’s longtime manager is auctioning off his collection, including many works by the YBA.

Frank Dunphy was manager to cantankerous bad boy of the Young British Artists, Damien Hirst, for decades—and in the process accumulated hundreds of works by the artist. They run the gamut from butterfly works to spin paintings to pill cabinets to sketches drunkenly jotted down at the infamous Groucho Club in Soho. The two-day sale, which features around 200 works, a portion of which are by Hirst, will take place in September at Sotheby’s. When asked by the Guardian why he was selling, Dunphy said it was time to “downsize,” adding that “time waits for no man and the time has come to say goodbye to some of the art, though not the memories nor the friendships.”

Until his retirement in 2010, Dunphy was the straight-laced numbers guy to Hirst’s unfiltered id—Sotheby’s Europe Chairman Oliver Barker told the Guardian that he had a “Midas touch” and said that “Behind every great creative genius is a Svengali-type character who helps unleash and channel their brilliance.” For Hirst, that Svengali was Dunphy, who proved his money-making bonafides when he convinced the artist to bypass his dealers and sell new work directly through Sotheby’s. The result was “Beautiful Inside My Head Forever,” the 2008 sale that reaped £111.5 million (or $200.8 million at the time), setting a new record for the largest single-artist auction.

The sale of Dunphy’s collection is expected to bring in £8.4 million, or $11.05 million.