By most accounts, Marcus Goldman, the man who founded Goldman Sachs in 1869, was not much taken by things "cool". A former schoolteacher and the son of a peasant cattle dealer, Mr Goldman was obsessed with making daily calls to wholesale diamond and leather merchants. From them, he bought promissory notes, a forerunner of commercial paper. Mr Goldman stuffed the IOUs he received from the merchants inside his hat for resale to banks later in the day.

An outfit that started in a cramped basement space next to a coal chute on Pine Street in Manhattan has, 131 years later, developed into one of the world's most powerful investment banks.

It is still evolving faster than ever. Today's Goldman, in which former Irish EU Commissioner Mr Peter Sutherland is chairman of Goldman Sachs International, is hugely different from what it was only a year ago, when the firm ended its partnership structure and became a public company.

The debate about partnership versus public-company status that so consumed the firm's partners - and caused so much bad blood - appears long gone. Mr Jon Corzine, the firm's co-chairman, who was forced to fall on his sword as the initial public offering went through, is running for the Senate in New Jersey.

The group is now under the leadership of three men: Mr Hank Paulson, chairman and chief executive officer, and the young duo of Mr John Thain and Mr John Thornton, co-chief operating officers.

"We are very committed to having all our employees owning stock going forward. Public or partnership is yesterday's debate," says Mr Thain, in the first interview he and Mr Thornton have given since the IPO.

Instead, the firm that is noted for obsessiveness has found a fresh obsession: managing itself. Goldman's business no longer fits inside one man's hat - or even the heads of three high-powered executives. The task is to find ways to maintain quality, lines of communication and a distinctive corporate culture at a time of growing global reach.

One response is the "coolness" committee, known formally as Goldman's lifestyle committee. To be sure, this is coolness Goldman fashion. To keep junior employees from leaving for dot.com start-ups, other Wall Street investment banks have started to provide free laptops and concierge services.

Goldman's younger, but typically serious, staff seemed to be more concerned with getting clearer orders from their superiors.

"We wanted to get the reaction of the junior people," says Mr Thornton, who, with Mr Thain, recently visited the committee, "and the two most important things they said were that we want better mentoring and we want our people to be better leaders."

The dialogue highlights what Mr Thain and Mr Thornton say are the most important issues facing Goldman - recruiting, training and motivating employees, especially new ones. Mr Thain says that when he and Mr Thornton were appointed to work alongside Mr Paulson, they said they would tackle four important issues: strategy, capital allocation, client work and people development. In practice, Mr Thain says: "We have spent a large amount of time on people development. It has been our most important issue."

By year's end, Mr Thain and Mr Thornton want to have added 3,000 staff to the current total of approximately 15,000. Assuming more than 1,000 staff leave during the next seven months, that means Goldman has to attract more than 4,000 recruits, an average of about 107 a week.

Mr Daniel Neidich, a management committee member, has been appointed to head a committee on recruiting talent looking at the recruitment process. Mr Thornton says the existing approach to recruitment "has been good for us, but not sufficient for the future. We still recruit business-by-business by region, and we want to create a state of the art recruiting process". The result is that Goldman has been ignoring key talent pools. Mr Thornton, who has helped make Goldman an Asian powerhouse, points to Tsinghua University in China. "We have never hired a single person from Tsinghua, and we should be aiming to hire 50 or more a year."

Goldman concedes that, as it expands rapidly, it faces a challenge in maintaining staff quality. Some also wonder if the firm's obsessiveness about "doing whatever it takes to get the job done" may wilt as it grows.

Critics point to the World Online controversy as evidence that the bank is taking on work it would previously have shunned.

Goldman denies any wrongdoing in helping to take the Internet service provider public in Amsterdam. Privately, though, senior executives concede the offering, which traded disastrously after the IPO, did not meet Goldman's standards.

People issues are all the more urgent, because Mr Thain and Mr Thornton say they are braced for the departure of a larger-than-normal number of senior colleagues. At the same time, former partners are being allowed to sell their shares and Goldman has put special measures in place to ensure that the company's stock price is not wobbled.

"We are very conscious of the fact that our single biggest challenge is managing growth and all of its dimensions," says Mr Thain. "We have to spend a lot of time on the monitoring and development of our senior people as leaders. We have not done a terribly good job of leadership development."

Hence, the duo has set up the Pine Street board - named after the group's humble first address - to develop a management-training programme for its 700 or so managing directors.

The two say they have been spending much of their time making sure that the careers of their high-flying but more junior colleagues are being developed in the right way. Mr Thain and Mr Thornton say they were sent to co-manage Goldman's European operations in the mid-1990s in part to see if they could work together. They are keen to develop their colleagues' careers in a similar fashion. "We want to develop a cadre of people who can thrive and help lead a truly global firm," Mr Thornton says.

The rapidly changing nature of the group has become another obsession at Goldman. In the face of the extraordinary boom in individuals trading stocks in the US and Europe, Goldman looks set finally to break a taboo at the bank and dip a toe into the retail broking market.

Using the technology it acquired through the takeover of Hull Group, a derivatives-trading firm that Goldman paid $550 million for last year, the firm intends to become an aggregator of retail trades.

But, despite this departure, Goldman will not neglect its traditional customers. Eager to get more business from wealthy individuals, it is set to launch new online client services via a new service, currently referred to internally as gs.com.

Mr Thornton argues that no institution has yet established a "commanding share of the management of money of wealthy individuals" and that Goldman hopes to win a lead position in the market for individuals with more than $25 million.

The service is likely to be launched in the autumn. As the trading facilities develop, it might be offered to less wealthy clients. "Eventually you will be able to trade everything," Mr Thain says.

"This is just a logical step," Mr Thornton says. Despite its new obsessions Goldman still displays one constant: a desire to present radical change as part of a meticulously planned evolution.