In the annals of the frustrating fight against impotence, men have ingested rhino horn dust, performed elaborate dances, employed vacuum hydraulics, and chanted what one historian called "protective spells" that went like this: "Get excited! Get excited! Get an erection!" 

But none of those remedies were as successful — or crazy — as what one physician did at a urological conference in 1983. Before presenting his research to hundreds of doctors, Giles Brindley injected — yes, injected — his penis with a chemical that made it erect. On stage, he dropped his pants to demonstrate the results.

"There was not a sound in the room," a urologist recalled in a scientific journal. "Everyone had stopped breathing." 

Viagra, approved by federal regulators 20 years ago, became a pharmaceutical and cultural phenomenon at a very odd moment — amid President Bill Clinton's sex scandal with intern Monica Lewinsky, when one of Clinton's fiercest and oldest political enemies became a TV pitchman for the drug. 

Bob Dole, the conservative Republican senator from Kansas. 

"Dole may have lost the presidential election," Meika Lee wrote in "The Rise of Viagra," "but this time he returned victorious," capturing the country's attention — and late night TV laugh lines — as "the one bringing respectable sexuality back to America and American politics."

And you thought things were strange now. 

The moment, in retrospect, came about from a virile accident. Pfizer was developing a chemical compound called sildenafil citrate for high blood pressure. It was not going well. 

"It was so close to failure that people weren't coming to the meetings," Pfizer chemist David Brown told Bloomberg in an oral history of the drug. 

The scientists kept going, hoping for a breakthrough. And then, finally, one emerged when they tested the drug on miners. But it had nothing to do with their blood pressure. 

"Is there anything else you noticed you want to report?" Brown recalled asking the miners. "One of the men put up his hand and said, 'Well, I seemed to have more erections during the night than normal,' and all the others kind of smiled and said, 'So did we.'" 

The side effect wasn't really a side effect: It was the jackpot. 

Prizer switched gears, studying the compound for impotence. Men were given the drug in lab settings and instructed to watch dirty movies. 

"They were fitted with what was called a Rigiscan — you can imagine what that does," Brown told Bloomberg. "At the end of the week, we had to get the drugs back from them, anything that was unused. Some of them would not give the drug back." 

The drug wound its way through the approval process. The jokes began almost immediately. "You must have heard them," Lee wrote. "In nursing homes, Viagra keeps male patients from rolling out of bed. Did you hear about the first death from an overdose of Viagra? A man took 12 pills and his wife died. Viagra is now being compared to Disneyland — a one-hour wait for a two-minute ride." 

And so on. 

But Viagra really worked wonders. It became such a hot commodity around the world that the CIA used it in Afghanistan to influence tribal elders in need of a little lift.