"Feeling that he'd reached the end of his style's potential, he shifted in 1967 to black and white images that dealt with challenging perspectives and "spatial conundrums." Some critics dismissed this work as simply disorienting; others declared it Held's finest achievement to date. By the late 70's, he had re-introduced colour to his work."
"When you’re making something you’re always focused on finishing it. And then when you step back you start seeing all of these things which you didn’t plan. You know, the sunlight that comes in at two o’clock, the shadow of someone walking by something. You’re sitting down and you look up and see something that you hadn’t even remembered you put there—and you didn’t really put it there—it got there because of other reasons. That view through to Al’s painting, it was like, “This is the end, I can leave now.” I always thought there were lots of connections with his work and my work. He didn’t really think that. I think he knew that we both liked complexity. There was a lot of geometry. There was a lot of torquing of space."
Judy Pfaff, on Al Held
via Art 21.. here