“Serge Lang, 1927–78200519ya § Part 1: Paul Vojta, University of California, Berkeley”, 2006 ():
…During my time at Yale, I gave 2 or 3 graduate courses. Serge always sat in the front row, paying close attention to the point of interrupting me midsentence: “The notation should be functorial with respect to the ideas!” or “This notation sucks!” But, after class he complimented me highly on the lecture.
While on sabbatical at Harvard, he sat in on a course Barry Mazur was giving and often criticized the notation. Eventually they decided to give him a T-shirt which said, “This notation sucks” on it. So one day Barry intentionally tried to get him to say it. He introduced a complex variable Ξ, took its complex conjugate, and divided by the original Ξ. This was written as a vertical fraction, so it looked like 8 horizontal lines on the blackboard. He then did a few other similar things, but Serge kept quiet—apparently he didn’t criticize notation unless he knew what the underlying mathematics was about. Eventually Barry had to give up and just present him with the T-shirt.
Once, close to the end of my stay at Yale, I was in his office discussing some mathematics with him. He was yelling at me and I was yelling back. At the end of the discussion, he said that he’d miss me (when I left Yale). Now that he has left, I will miss him, too.