Goldman Sachs' 2nd-most-powerful executive is going to be the public face of the bank for a while

Goldman Sachs CEO Lloyd Blankfein has disclosed he has cancer, and that he will reduce some of his previously planned travel during a period of treatment.

In a letter to shareholders, Blankfein revealed that he has a "highly curable" kind of lymphoma and will undergo chemotherapy in the coming weeks in New York.

Gary Cohn, chief operating officer at Goldman Sachs, will fill in for Blankfein at various public events during the period, according to a person familiar with the matter.

Blankfein had been due to speak at a New New York event last night, but cancelled at the last moment. Cohn took his place. 

Cohn is a safe pair of hands. He has spent 25 years at the bank. He has served as a top exec at Goldman alongside Blankfein since 2006. 

He also has an incredibly inspirational backstory, which is detailed in Malcolm Gladwell's best-seller "David And Goliath." 

As a kid growing up in Cleveland, Cohn found out he had dyslexia, a reading disorder. He struggled in school. By the time he was in sixth grade, he had attended four different schools. Teachers and classmates had written him off as an "idiot." Cohn has even said publicly that he was a "horrible" student.

What's more is his teachers were unsure of his trajectory in life. One teacher even told his parents if they were really lucky, he might grow up to be a truck driver.

Cohn graduated from high school. He also graduated from American University in 1982.

After college, though, Cohn didn't immediately have a job or any interviews lined up. He did have "passion for financial markets," but that was pretty much it. By July he took a job "to appease" his father selling window frames and aluminum siding for the home-products division of United States Steel in Cleveland.

Around Thanksgiving, he went on a work trip to the company's offices in Long Island. Cohn persuaded his manager to give him Friday off to visit New York City for the first time. There he headed for Wall Street and the commodities exchange at Four World Trade Center. From the observation gallery, he watched the action in the trading pits with other Wall Street hopefuls.

That's when he came up with a clever plan to make an introduction to one of the brokers. He left the visitors' gallery and waited by the security entrance to the trading floor for a few hours. Nothing happened. He was about to give up.

"And then literally right after the market's (sic) closed, I see this pretty well-dressed guy running off the floor, yelling to his clerk, 'I've got to go, I'm running to LaGuardia, I'm late, I'll call you when I get to the airport,'" Cohn told Gladwell in the book. "I jump in the elevator, and say, 'I hear you're going to LaGuardia.' He says, 'Yeah,' I say, 'Can we share a cab?' He says, 'Sure.' I think this is awesome. With Friday afternoon traffic, I can spend the next hour in the taxi getting a job."

It was truly a brilliant move, one most people wouldn't have the guts to make.

It turned out the man Cohn was sharing the cab with was also running the options business for one of the big brokerage firms. Cohn didn't know what an option was, but he pretended as if he did.

"I lied to him all the way to the airport," Cohn told Gladwell. "When he said, 'Do you know what an option is?' I said, 'Of course I do, I know everything, I can do anything for you.' Basically by the time we got out of the taxi, I had his number. He said, 'Call me Monday.' I called him Monday, flew back to New York Tuesday or Wednesday, had an interview, and started working the next Monday. In that period of time, I read McMillan's "Options as a Strategic Investment"book. It's like the Bible of options trading."

(By the way, Gladwell notes, it still takes Cohn about six hours to read 22 pages.)

After a few years working on the floor of the commodities exchange, Cohn was contacted by Goldman Sachs. In 1990 he accepted a position in Goldman's commodities trading unit, J. Aron & Co., which is where Blankfein got his start. In 1994 he was made partner - one of the most coveted titles on Wall Street.

Now he holds one of the top spots at the Wall Street investment-banking giant. He has even said he wouldn't be there without his dyslexia.

"The one trait in a lot of dyslexic people I know is that by the time we got out of college, our ability to deal with failure was very highly developed," Cohn told Gladwell. "And so we look at most situations and see much more of the upside than the downside. It doesn't faze us. I've thought about it many times, I really have, because it defined who I am. I wouldn't be where I am today without my dyslexia. I never would have taken that first chance."