It was just a carton of soap pads. Then Andy Warhol copied it.

After that, it became an icon that forced everyone to ask anew, What is art?

Arthur Danto, Columbia philosophy professor and art critic for The Nation, has spent more than three decades examining the effect of Warhol’s “Brillo Box” on our understanding of art. And on Jan. 31, in what he called “the last of the ‘Brillo Box’ talks,” Danto mused again on what makes art art.

His Penn Humanities Forum lecture on “Three Brillo Boxes” — moved to Bodek Lounge in Houston Hall due to a last-minute scheduling snafu — looked at the original commodity, Warhol’s reproduction of it and a later expropriation of Warhol’s work.

Danto noted that Warhol’s work was originally part of a larger installation of packing crates for several familiar products. “That ‘Brillo Box’ became the star of the show was due to the box’s superior design,” he said, thus undermining what he called Pop Art’s desire “to reach a plane where aesthetics doesn’t matter.”

Moreover, that design, created in 1964 by failed Abstract Expressionist artist James Harvey, was itself laced with symbolism and meaning, which made it difficult for critics to draw a bright line between the box as box and the box as art. “I had to either find another [criterion] to drive a wedge between the two or accept Harvey’s box as art,” Danto said of his original reaction to the Warhol box.

Danto also mulled the symbolism in the Brillo box design, with its bold red and blue letters on a field of white — “a flag of patriotic sanitation,” he called it. He also judged it far superior to the current Brillo design. “Harvey’s box is a celebration of Brillo, while the current design doesn’t celebrate Brillo at all.”

As for that third box — a reproduction by Mike Bidlow — Danto called it “the emblematic work of the 1980s,” which saw the emergence of a movement in which artists recreate famous works by others. “It’s a way of grappling with the end of art,” Danto said.