For our first meeting Mark showed up in a T-shirt with the International Phonetic Alphabet printed on it, and I soon discovered that all his T-shirts were a form of self-expression. In fact, everything he owns somehow advertises his interests to the world. On his minivan he has a KLI license plate holder and an LNX sticker (proclaiming himself a user of the Linux operating system). On the vest he wears most days, he displays his three Klingon certification pins; membership pins for the Dozenal Society (“they advocate switching to a base 12 system from the base 10 system we use for numbering”), Mensa (“it’s a way for insecure people to feel better about themselves”), and the Triple Nine Society (“a more extreme kind of Mensa”); and a button he made that says “If you can read this you are standing too close” in Braille.

I usually met with Mark at a kosher pizza place. He’s an Orthodox Jew who follows all the rules, but jokes that he would be an atheist “if I weren’t such a scaredy-cat.” He is slender and jittery, one knee constantly bouncing as he talks in a speedy patter. His eyes convey both friendliness and sadness, as if he hopes you will like him but wouldn’t be surprised if you punched him. He never finished his Ph.D. in computer science, and he has had trouble holding down a job, to which he credits his attention deficit disorder (“It’s not an excuse; it’s an explanation”). He cares for his children while his wife, a physician, works, and he teaches computer programming part-time at a yeshiva in Newark. While many bright people like Mark tend to blame the world for not rewarding them more heartily for their smarts, he accepts his own responsibility in the matter. He knows a lot, but not much of it is career making. He is, as he might put it, a polymath of esoterica. His other interests include knot making, typography, mathematical knitting, and calendrical systems. We flew to Phoenix together, and when the plane took off, he pulled a book out of his duffel bag titled Science from Your Airplane Window.