Winter had not even officially arrived, and already the boys were getting restless. Days after a blizzard buried Springfield, Massachusetts in snow, a highly contagious case of cabin fever tore through the International Young Men’s Christian Association (YMCA) Training School. The unruly students roughhoused in the halls and wouldn’t quiet down. Even a modified game of football in the gymnasium failed to burn off their excess energy.

James Naismith, a second-year graduate student who had recently been appointed a physical education instructor, took up a teacher’s challenge to develop a game that would keep the pupils active in the winter months. The 30-year-old Canadian native drew on his knowledge of rugby, lacrosse and a childhood game known as “duck on a rock,” which combined tag with throwing, to dream up a new sport.

On December 21, 1891, Naismith cleared the athletic equipment off the gymnasium’s wooden floor and picked up a soccer ball. He asked a janitor for two square boxes, but the best the custodian could do was a pair of peach baskets, which Naismith mounted to the lower rail of the gym’s balcony, about 10 feet off the ground.

“I called the boys to the gym, divided them up into teams of nine and gave them a little soccer ball,” Naismith recalled in a 1939 radio interview that aired on WOR-AM in New York City. “I showed them two peach baskets I’d nailed up at each end of the gym, and I told them the idea was to throw the ball into the opposing team’s peach basket. I blew the whistle, and the first game of basketball began.”

The only rule Naismith gave to the boys was to get the soccer ball into the bottom of the peach basket, from which it was retrieved by students in the balcony. The lack of guidelines, however, soon proved problematic. “The boys began tackling, kicking and punching in the clinches. Before I could pull them apart, one boy was knocked out, several of them had black eyes and one had a dislocated shoulder. It certainly was murder,” Naismith said in the 1939 broadcast, which is thought to be the only existing recording of his voice.

The game may have been rough, but it was fun. “After that first match, I was afraid they’d kill each other, but they kept nagging me to let them play again, so I made up some new rules,” Naismith recalled. The physical education instructor sat down and devised 13 rules for his invention and gave them to his secretary to type up onto two pages, which he posted in the gym.

The most important rule was that there could be no running with the soccer ball. It could only be thrown or batted from the spot where it was caught. “That stopped tackling and slugging,” Naismith said. “We tried out the game with those rules, and there were no casualties. We had a fine, clean sport.”

Naismith had considered instituting free throws as penalties for teams committing fouls but found that “after a little practice, a good thrower could convert it into a goal almost every time.” Instead, the original rules called for a player making two consecutive fouls before the scoring of a basket to sit out until the next goal. Three consecutive fouls by a team resulted in a score for the opponents. There was to be “no shouldering, holding, pushing, tripping or striking in any way” in the game, which was composed of two 15-minute halves.

In spite of student suggestions that he call the game “Naismith Ball,” the modest inventor gave the sport a two-word moniker—“basket ball.” In an article that ran in the January 15, 1892, edition of The Triangle, which was distributed to YMCAs around the country, Naismith detailed his 13 rules for a “new game of ball” that “calls for physical judgment and co-ordination of every muscle and gives all-around development.”

Naismith’s brainchild caught on quickly at other YMCAs and spread to college campuses to become the fastest-growing game in the history of sports. Basketball was not only for the boys, either. From the sport’s advent, women dressed in blouses and bloomers played the game that the Boston Globe found in 1893 to be a “very fair feminine substitute for football.”

In 1898, Naismith was hired as the first men’s basketball coach at the University of Kansas. (Ironically, he is the only men’s coach in the program’s history to have a losing record.) During his tenure, he saw his 13 rules begin to evolve. The bottoms were eventually cut out of the peach baskets to make them hoops, and free throws ultimately gained favor to become part of the game. Dribbling was introduced in 1901. While Naismith initially wrote that team sizes could range from 3 to 40 players, depending on the size of the floor space, five-player squads became the norm.

Naismith’s original 13 rules—complete with a hand-written line edit—now reside at the University of Kansas after alumnus David Booth, who grew up in eyeshot of the campus, purchased them at auction in 2010 for $4.3 million. The price fetched by the two yellowing pages even eclipsed that of a copy of the Emancipation Proclamation signed by Abraham Lincoln and once owned by Robert Kennedy that was up for bid at the same auction. Earlier this year, a new display featuring the rules was unveiled in a 32,000-square-foot building adjacent to the university’s basketball arena.

Basketball rule books have gained considerable heft since Naismith concocted the first guidelines 125 years ago. The National Basketball Association’s Official Rule Book is now more than 65 pages long and dictates everything from where coaches may stand on the sideline to the need for players to tuck in their shirts to something that Naismith could never have dreamed of—the use of instant replay to aid referees.