Professor Kenneth Arrow, a titan of economic theory and Nobel laureate for economics, died yesterday at the age of 95. The New York Times published an excellent obituary. Economics Nobel laureate Al Roth published a blog post about this, the comments on which I recommend reading as well. Finally, Kevin Bryan started a monumental series of four posts on his blog, explaining patiently and deeply the contributions Arrow made to economics. Here is the first of these posts.

UPDATE 2017-02-25: Here is a concise and heartfelt tribute by Lawrence Summers, a nephew of Arrow. Two personal reminiscences in this are so compelling that I am taking the liberty of quoting them here:

I remember like yesterday the moment when Kenneth won the Nobel Prize in 1972. Paul Samuelson—another Nobel economist and, as it happens, also my uncle—hosted a party in his honor, to which I, then a sophomore at MIT, was invited. It was a festive if slightly nerdy occasion.

As the night wore on, Paul and Kenneth were standing in a corner discussing various theorems in mathematical economics. People started leaving. Paul’s wife was looking impatient. Kenneth’s wife, my aunt Selma, put her coat on, buttoned it and started pacing at the door. Kenneth raised something known as the maximum principle and the writings of the Russian mathematician Pontryagin. Paul began a story about the great British mathematical economist and philosopher Frank Ramsey. My ride depended on this conversation ending, so I watched alertly without understanding a word.

But I did understand this: There were two people in the room who had won Nobel Prizes. They were the two people who, after everyone else was exhausted and heading home, talked on and on into the evening about the subject they loved. I learned that night about my uncles—about their passion for ideas and about the importance and excitement of what scholars do.

[…]

Kenneth knew more about everything than most know about anything, but he never flaunted his intelligence. It was another lesson for me when, many years ago, a paper was published correcting a famous analysis published by one of Kenneth’s teachers. At the time, it created a stir. I asked him what he thought. He said quietly that he had known of the error for decades, but such was his respect for his teacher that he did not publish his insight.