"It's the secret of life."

Not long after Duane Christensen, as it turned out, my father-in-law Steve died.

Steve had been wheelchair-bound for 13 years due to an extremely rare neurological condition (he had first begun to show symptoms twenty years ago; he was finally diagnosed last year). Despite the fact that his world slowly and inexorably shrank, so that his bike rides, his camping excursions with his family, his trips to the park, were all eventually taken away, Steve continued to show not just what is often euphemistically called a "good attitude," but a downright disarming interest in life, and especially the lives of the people around him.

This was partly just a default stance of his, but it was also a conscious practice, a cultivation of gratitude and engagement, which has taught me a great deal. He did not disguise the fact that his life held great frustrations. But in his late 20's, during a profound struggle with depression, Steve had intentionally adopted a position of thankfulness, in which complaint was at best a tool with passing relevance and at worst a distraction. It was a kind of joyful discipline.

As a grad student, Steve had studied mathematics under J. Richard Büchi, who made significant contributions to automata theory and category theory. During Steve's last months I tried to take advantage of his expertise about these topics, but many of the conversations seemed to drift from mathematics into anecdote, and I found myself more eager for the story than for the math. He told me, for instance, that while reading a paper by Hans Läuchli, he'd realized that "You had to read papers with a pencil in your hand;" sometimes a lemma might be stated without being demonstrated, but that the significance of the paper might depend upon some detail in the (implied but unstated) proof. This seemed an observation that pertained as well to reading philosophy or a novel -- not the note-taking per se, but the need to always read between the lines. At one point he offered a high-level characterization of category theory: "Set theory is concerned with mathematical objects. Category theory is concerned with functors, with arrows between objects." This is, of course, far too inexact to serve by itself as a two-sentence summary of category theory, but it brought into focus something about Steve: what appealed to him was not definition but connection. He was preoccupied with the human beings who were or had been in his life, whether from his childhood or the last time he had been in the hospital. His concern with relationship became clear in his way of telling stories, which as he grew older reminded me more and more of Herodotus -- frequently there were many implied transitions of the form of "that reminds me of...," in what seemingly threatened to be an infinite deferral of "the point of the story;" but when they came full circle, one realized that there had been an implicit wholeness to the shape of the chain of anecdotes from the beginning. The connections could be almost anything: the color of someone's hair, the age of two people at the time of some important event, the city where something had happened. His recollections of the 1971 Tarski Symposium in Berkeley, for instance, were not primarily about the topics discussed, but about the people -- the mathematician he'd been too shy to introduce himself to; his cousin once removed, a year and a half old at the time, who was then living in Berkeley and who he'd met. When I said to him that these narrative connections reminded me of functors in Category Theory, the mathematical relevance was doubtless strained, but Steve smiled and understood.

Another of Steve's great loves was music; he listened to the Metropolitan Opera every Saturday morning, and the Big Band Swing program on the local radio station Saturday night. Though not an especially observant Jew, toward the end of his life he made a point of singing the haggadah from his youth at our last family Passover. He went to chamber music series and the local Symphony, and I am very grateful for the memories of our trips to the yearly bluegrass festival. Once I asked him whether he thought his appreciation of mathematics and of music were related. "I've heard they're supposed to be," he smiled. But this wasn't the aspect that interested him. Although he'd studied Hindemith, and had a rich understanding of musical theory, his conversation about music made no attempt to wrench the ineffable into expression. Rather, he'd move on to music history: either his own (say, the fledgling soprano whose performance he'd been impressed by, whose career he'd followed, and who went on to sing at the Met), or an anecdote he knew about Clara Schumann or Jacqueline du Pré. I sometimes thought that his connections with these people were as real as those with people he knew.

The stories were always there, but they became more and more brief. Toward the end of his life, as he settled with the realization that he would die, Steve more and more often would lapse into silence, and his remarks were more like hints of a whole that had to be inferred. He was wrestling with the last and greatest occasion for depression, and doing it with an astounding dignity and vulnerability. More and more, the ineffable came to the fore, and stayed there. During my last conversation with Steve, a week before he died, I happened to mention something about regretting having fallen out of touch with old friends. I wish I knew how to reach them again, I said; I wanted to preserve my relationships. Steve was a good listener and rarely interrupted, but at this word Relationship he cut in and said, in a tone of gravity and wonder, "It's the secret of life."