Back in the mid-1980s I was a PhD candidate at the Colorado School of Mines working with Norm Bleistein and Jack Cohen at the Center for Wave Phenomena. Walt was a professor at CSM. Each PhD candidate had to go through a qualifying exam that involved a committee and, in those days (still?), one member of the committee had to be a student. I was assigned the committee for my good friend Sebastian Geoltrane, a tall, lanky Frenchman who was fearless and fiercely talented at many things. I once saw his long legs poking out from under his small euro sedan near the CSM campus and heard the familiar voice ranting in French. He was casually taking on the job of pulling and repairing the transmission. Another time we went skiing at A-basin during an ice storm that he left the mountain a glazed death trap. Seb swooshed and zagged like it was powder while I tumbled, skidded, and crawled seemingly miles behind him.
Anyway, Seb's qualifier came along and Walt was on the committee along with an all-star cast of professors. In the usual fashion, there had been a written exam that was now further discussed along with anything else in the universe the committee felt like asking. Seb was a wonder. A whirling dervish of activity deriving equations, sketching solutions to fantastic problems, plumbing tensors to any depth, and waving those long arms in dismay that such childish questions should even arise. I think I asked him something about a cosine, just to say something. Finally, the session was over and Sebastian was asked to leave while we deliberated. The room was quiet for what seemed like a long time.
Then Walt said, "I think we should flunk him." The room rumbled with objection till someone actually asked, "Why?". Walt responded cool and calm, "We'd be doing him a favor. He should be at MIT." The joke passed and so did Sebastian.