There are a couple of ways to hang this piece: at floor level and set up like a giant tic tac toe board, or at eye level like graph paper.

It is definitely the most fun tic tac toe or graph paper I’ve ever seen. I might have passed geometry if this was how we learned it.

Flavin did this piece, as the title explains, in honor of Leo Castelli’s gallery’s thirtieth B-day. A bunch of Flavin’s work was dedicated to other people, like untitled (to Barnett Newman) two. Like when you give your mom a watercolor every Mother’s Day. But that isn’t to cheapen it, Dan Flavin making a light installation for you is like, well, like a really famous artist giving you a trust fund that also looks pretty in your house. And Leo Castelli basically made Dan Flavin’s career, so it’s the least Danny could do.

Castelli was a mammoth figure in the New York art world who brought Donald Judd, Cy Twombly, Ed Ruscha and many other A-list artists to Europe, museum collections, and art history textbooks. He was also quite a personality, known to charm people with one sentence: he met the new cultural counselor of the French Embassy in New York at dinner once and she wrote a biography about him nearly 30 years later. He was reportedly unlucky with women as a boy in Trieste until he had session with a Freudian psychoanalyst who suggested he consider the woman’s point of view—since then he’s been one of those west-continental Don Juans of legend. He arrived in New York by boat when Paris fell to the Nazis.

It’s from those straight-up mythological origins that he came to preside over the rise of American Minimalism from the front room gallery of his family home. Castelli was the first gallerist in New York to pay the artists on a monthly basis regardless of whether or not their art sold, bankrolling early forays into experimental art. He basically brought Flavin to market, and is indirectly responsible for the magnum opus that is the Hotline Bling music video.