Rich Cohen is the author of “ The Chicago Cubs: Story of a Curse ,” from which this essay is adapted.

The home run is the greatest play in American sports — not only the most efficient way to put numbers on the board but also the most beautiful. The slugger swinging from his heels, driving the ball as a hammer drives the nail deep into the wood. Boom. Just like that, it's a white dot in the sky, a God-ball that ascends to heaven, breaking a million hearts as it goes. But the homer was not always loved.

Its career has waxed and waned. In the steroid era — the mid-'90s to 2003, say — players grew beefy and offensive stats ballooned and homers fell in bunches. Sammy Sosa, Mark McGwire and later Barry Bonds broke the single-season home-run record set by Roger Maris (61). Players who'd always hit 20 were suddenly hitting 50. Dugouts filled with behemoths who had giant forearms and necks, monstrous thighs straining the fabric of monstrous baseball pants. It ruined the aesthetics. Ted Williams's fluid elegance turned into something muscular. It separated players from fans, alienated some of us: These guys looked like members of a different species.

All this culminated in a scandal that led to more efficient drug testing and stiffer penalties. Managers learned to play small ball again — bunt, double steal, a run manufactured in the way of a piece of handmade pottery. But over time, because there's nothing more satisfying nor effective, the home run returned. This season, players swatted 6,105, breaking the record set in 2000. Experts credit new styles of hitting — launch angles, escape velocity. Some suggest the balls themselves have been juiced. In any case, we're living in a golden age of the long ball, a new chapter in the greatest of all baseball stories, the one about how the game went from small to big, dead to alive, in the process becoming the national pastime.

In the first days of the sport, baseball was about getting guys on base and putting the ball in play. It relied on creativity and gamesmanship, and it was personified by Ty Cobb. He used a thick bat that didn't taper at the handle, probed the defense for holes, placed the ball between fielders. He spent hours and hours perfecting many varieties of bunt. His real work began only when he got on base. He did not have to rely on other players to move him from second to home. He stole his way. His appearance matched his style — skinny and neat, carefully tucked, sharp-tongued, moody and mean. He changed his batting style to fit the situation. In 1912, in 609 plate appearances, he struck out just 30 times.

Then, while the doughboys returned from Europe, the Red Sox worked out the deal that sent Babe Ruth to the Yankees, where manager Miller Huggins, recognizing the breakthrough represented by the Babe's unique swing — he started at his heels, ended in the sky — moved him from the pitcher's mound into right field. He wanted Ruth's bat in the lineup every day. In 1919, while still in Boston, Ruth hit 29 home runs; the next year, with the Yankees, he hit 54. Before him, the most anyone had ever hit in a season was 27. In 1920, Ruth, all by himself, hit more homers than any team in the majors. This was not just an aspect of the old game done bigger; it was a new game altogether.

The home-run-besotted baseball we play today was personified by Ruth: bighearted, sloppy, gregarious, warm. He did not just drive the ball out of the park; he drove it way out of the park. He did not just hit a home run but promised beforehand that he would hit a home run. He was like Muhammad Ali, full of swagger and talk. He stood in the on-deck circle swinging three bats, which were fat at the top but skinny at the handle — harder to control but easier to whip through the strike zone. The sound the ball made off his bat was different. Sharp. Concussive. It screamed in pain. He did not love strikeouts but didn't fear them, either. They were the price of power. He'd gladly trade three Ks for one home run. He led the league in strikeouts five times, but he led the league in home runs 12 times.

Major League Baseball was already in its 45th season when Ruth broke through. Why had this innovation taken so long? Many people believe that the ball was remade around this time; supposedly, the string inside was wound more tightly, turning it into a kind of superball. But Albert Spalding, whose company manufactured every ball used in the majors, denied it. He said the design had not changed since 1910, when the cork center was added.

If it was not the ball, maybe it was the new bats — tapered at the handle, heavy at the top. Once you started to swing, the bat seemed to go on its own. Easier to propel, harder to control: home runs and strikeouts. And there was the swing itself — the stance and the stroke Ruth had been free to pioneer because he'd been a pitcher, and who really cares what a pitcher does at the plate?

But the greatest change was probably the ball's condition. In the past, a ball was kept in play until it was lost in the stands or fell apart. By the late innings, it was the color of dirt, nearly impossible to see. It left a pitcher's hand and then vanished into the catcher's mitt. A tremendous catalogue of trick pitches made this possible: spitball, licorice ball, elm ball, shine ball, paraffin ball. Details varied but the intent was always the same: Change the spin, confuse the flight. A hitter expects it to break this way, it goes that way instead.

Then Ray Chapman, the Cleveland Indians' shortstop, stepped to the plate at the Polo Grounds, where the Yankees played till Ruth's fame financed the new stadium in the Bronx. Carl Mays was pitching for New York that Aug. 16, 1920, and afternoon shadows were creeping in. He was a submarine pitcher, known for throwing junk, going after batters. Chapman was batting .308, but the ball was the color of smoke, indistinguishable from the gloaming. It was later decided that Chapman never saw the pitch, because he did not move, just froze as it climbed. The sound of the ball hitting his head could be heard all over the park. People screamed. Chapman dropped to his knees, then fell on his face. He was taken to a hospital, where part of his skull was removed. He died the next morning. He is the only player ever killed in the course of a Major League Baseball game.

After a series of emergency meetings, two rule changes were made. Now umpires had to replace the game ball as soon as it showed stain or any sign of wear. That's why you see the umps today turning the ball over between pitches. At the slightest imperfection, they replace it — usually more than 100 times per game. Another change forbade the spitball and its relatives: No more nicking the ball on your belt buckle to alter its spin, no more roughing it with sandpaper (emery ball) or polishing one side of it on your jersey while slicking the other side with dirt (shine ball). By the mid-1920s, the game ball, which had been dirty by the third inning, was snow-white for Ruth and his disciples. Easier to see, easier to hit.

Of course, the main harbinger of the homer era was probably the Babe himself. After "Heartbreak Hotel," no one wanted to be Perry Como. They wanted to be Elvis Presley. After 1920, no one wanted to be Ty Cobb. They wanted to be Babe Ruth. The old game had been about precision, strategy, incremental progress. The new game was about power, the single blast that busts open the piñata.

Cobb and hundreds of others who continued on in the classical way suddenly seemed obsolete. And they hated it, Cobb most of all. He was a withering critic of the new style and its great exemplar, the fat man. His sport had abandoned elegance for vulgarity. It's how the great silent-film directors felt about the talkies. Too easy, too simple. It destroyed virtuosity. Writers said Cobb envied Ruth, but Cobb insisted that any fool could hit the ball out of the park; he just didn't want to sacrifice batting average. He told a Detroit reporter: "I'll show you something today. I'm going for home runs for the first time in my career." On May 5, 1925, Cobb hit three home runs against the St. Louis Browns. The next day, he hit two more. At that point, no one, not even Ruth, had hit five home runs in two days. Cobb then reverted to slap hitting, because he believed that was true baseball.

The change in the game, from dogged and small to splashy and big, was about more than baseball. It was the zeitgeist. The culture has a way of remaking its games to match its obsessions. Dead ball had been perfect for pre-industrial, pre-global America. It was village and farm, the hick with the spitball, the yokel with the level swing. The game invented by Ruth was much more appropriate for the America coming into being, the modern nation that would go everywhere and do everything and overwhelm everyone with its weapons. Front-loaded and flashy like its cities and its factories and its music and its movies. Flamboyant, gaudy, easier to understand. Halfway to the modern NFL.

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