Last Sunday’s episode of “Mad Men,” that moody chronicler of the 1961 Zeitgeist, covered the launch of Pampers (“At 10 cents a pop you’d expect to be able to use it more than once.”), where the term “cuppa Joe” came from (the founder of Martinson’s Coffee), and Abstract Expressionism. Advertising honcho Bertram Cooper has acquired a painting, and some of the staff sneak into his office to see it. It turns out to be a Rothko, similar to this one (the whole episode radiates with oranges, echoing the work). “What’s it s’posed to mean?” “So it’s smudgy squares, huh?” “Maybe there’s a brochure here somewhere, something that explains what it means.” That’s the response. Until one of the copywriters says: “Maybe you’re just supposed to experience it. It’s like looking into something very deep. You could fall in.” Bingo. You can have a similar experience when the Academy reinstalls its Clare Booth Luce Gallery of Modern and Contemporary Art with “Decades of Abstraction: From the Collection of the Honolulu Academy of Arts,” which focuses on Abstract Expressionism, America’s first big impact on international art. Abstract Expressionism is the art equivalent of jazz—a pure American artform. The exhibition opens Oct. 2.