eynman tended to associate more with the mathematicians than the physicists at the Graduate College. Students from the two groups joined
each afternoon for tea in a common lounge  more English tradition transplanted  and Feynman would listen to an increasingly alien jargon. Pure mathematics had swerved away from the fields of direct use of contemporary physicists and toward such seeming esoterica as topology, the study of shapes in two, three, or many dimensions without regard to rigid lengths or angles. An effective divorce had occurred between mathematics and physics. By the time practitioners reached the graduate level, they shared no courses and had nothing practical to say to one another. Feynman listened to the mathematicians standing in groups or sitting on the couch at tea, talking about their proofs. Rightly or wrongly he felt he had an intuition for what theorems could be derived from what lemmas, even without quite under standing the subject. He enjoyed the strange rhetoric. He enjoyed trying to guess the counterintuitive answers to their nearly unvisualizable questions, and he enjoyed the physicist's favorite needle, the claim that mathematicians spent their time proving the obvious. Although he teased them, he thought they were an exciting grouphappy and interested in a kind of science that was getting beyond him. One friend was Arthur Stone, a patient young man attending Princeton on a fellowship from England. Another was John Tukey, who later became one of the world's leading statisticians. These men spent their leisure time in curious ways.
Stone had brought with him Englishstandard looseleaf notebooks. The Americanstandard paper he bought at Woolworth's overhung the notebooks by an inch, so he presently found himself with a supply of inchwide paper ribbons, suitable for folding and twisting in different configurations. He tried diagonal folds at the 60degree angle that produced rows of equilateral triangles. Then, following these folds, he wrapped a strip into a perfect hexagon. When he closed the loop by taping the ends together, he found that he had created an odd toy: by pinching opposite corners of the hexagon, he could perform a queer origamilike fold, producing a new hexagon with a different set of triangles exposed. Repeating the operation exposed a third face. One more "flex" brought back the original configuration. In effect, he had a flattened tube that he was steadily turning inside out.
He considered this overnite. In the morning he took a longer strip and confirmed a new hypothesis: that a more elaborate hexagon could be made to cycle through not three but six different faces. The cycling was not so straightforward this time. Three of the faces tended to come up again and again, while the other three seemed harder to find. This was a nontrivial challenge to his topological imagination. Centuries of origami had not produced such an elegantly convoluted object. Within days copies of these "flexagons"  or, as this subspecies came to be more precisely known, "hexahexaflexagons" (six sides, six internal faces)  were circulating across the dining hall at lunch and dinner. The steering committee of the flexagon investigation soon comprised Stone, Tukey, a mathematician named Bryant Tuckerman, and their physicist friend Feynman. Honing their dexterity with paper and tape, they made hexaflexagons with twelve faces buried amid the folds, then twentyfour, then fortyeight. The number of varieties within each species rose rapidly according to a law that was far from evident. The theory of flexigation flowered, acquiring the flavor, if not quite the substance, of a hybrid of topology, and network theory. Feynman's best contribution was the invention of a diagram, called in retrospect the Feynman diagram, that showed all the possible paths through a hexaflexagon.
Seventeen years later, in 1959, the flexagons reached Scientific American in an article under the byline of Martin Gardner. "Flexagons" launched Gardner's career as a minister to the nation's recreationalmathematics underground, through twentyfive years of "Mathematical Games" columns and more than forty books. His debut article both captured and fed a minor craze. Flexagons were printed as advertising flyers and greeting cards. They inspired dozens of scholarly or semischolarly articles and several books. Among the hundreds of letters the article provoked was one from the Allen B. Du Mont Laboratories in New Jersey that began:
"Sirs:
I was quite taken with the article entitled "Flexagons" in your December issue. It took us only six or seven hours to paste the hexahexaflexagon together in the proper configuration. Since then it has been a source of continuing wonder.
But we have a problem. This morning one of our fellows was sitting flexing the hexahexaflexagon idly when the tip of his necktie became caught in one of the folds. With each successive flex, more of his tie vanished into the flexagon. With the sixth flexing he disappeared entirely.
We have been flexing the thing madly, and can find no trace of him, but we have located a sixteenth configuration of hexahexaflexagon……"
The spirits of play and intellectual inquiry ran together. Feynman spent slow afternoons sitting in the bay window of his room, using slips of paper to ferry ants back and forth to a box of sugar he had suspended with string, to see what he could learn about how ants communicated and how much geometry they can internalize. One neighbor barged in on Feynman sitting by the window, open, on a wintry day, madly stirring a pot of JellO with a spoon and shouting "Don't bother me!" He was trying to see how the JellO would coagulate while in motion. Another neighbor provoked an argument about the motile techniques of human spermatozoa; Feynman disappeared and soon returned with a sample. With John Tukey, Feynman carried out a long, introspective investigation into the human ability to keep track of time by counting. He ran up and down stairs to quicken his heartbeat and practiced counting socks and seconds simultaneously. They discovered that Feynman could read to himself silently and still keep track of time but that if he spoke he would lose his place. Tukey, on the other hand, could keep track of the time while reciting poetry aloud but not while reading. They decided that their brains were applying different functions to the task of counting: Feynman was using an aural rhythm, hearing the numbers, while Tukey visualized a sort of tape with numbers passing behind his eyes. Tukey said years later: "We were interested and happy to be empirical, to try things out, to organize and reduce to simple things what had been observed."
Once in a while a small piece of knowledge from the world outside science would float Feynman's way and stick like a bur from a chestnut. One of the graduate students had developed a passion for the poetry of Edith Sitwell, then considered modern and eccentric because of her flamboyant diction and cacophonous, jazzy rhythms. He read some poems aloud, and suddenly Feynman seemed to catch on; he took the book and started reciting gleefully. "Rhythm is one of the principal translators between dream and reality," the poet said of her own work. "Rhythm might be described as, to the world of sound, what light is to the world of sight." To Feynman rhythm was a drug and a lubricant. His thoughts sometimes seemed to slip and flow with a variegated drumbeat that his friends noticed spilling out into his fingertips, restlessly tapping on desks and notebooks.
"While a universe grows in my head," Sitwell wrote,
"I have dreams, though I have not a bed
The thought of a world and a day
When all may be possible, still come my way." 
(Folds and Rhythms, pages 102105)
