Banks determine who succeeds and who fails. This is a bankers' maxim, used now against its authors by Sam Brown, the antiwar-moblilizer-turned-treasurer of the state of Colorado.

After two years of occupying an office that ised to be little more than a retirement haven for political hacks, Brown has earned the enmity and respect of Colorado's biggest banks.

He has increased the return on state deposits by instituting competitive bidding, and he has encouraged poor, students and family farmers by giving them a break on state business if they do.

Using money raised from private foundations, because the legislature wouldn't give it to him, Brown also is publishing a series of booklets comparing bank services and costs.

These activities and the publicity associated with them have made Brown the hottest Democratic property in Colorado, where the political tide appears otherwise to favor Republicans.

One GOP political aide, who says he believes that his party has an excellent chance to win both the governor-ship and a U.S. Senate seat in 1978, says bluntly: "The only Democrat who worries us is Sam Brown."

Brown, known as Samuel W. to his parents and the Harvard divinity school, is the son of a chain shoe store owner in Council Bluffs, Iowa. At California's University of Redlands he was a government student who in the mid-1960s positioned himself "several miles right of Barry Goldwater."

He came to the left through the National Student Association and the Vietnam war. In 1968 Brown seems more than seven years away from the demonstation. He is 33 now and thinking about running for mayor of Denver.

Unlike an earlier gereration of rebels who seemed to lack a cause, Brown and hundreds of other academic veterans of the peace movement turned to state and local government.

Brown arrived by way of a failed, romantic writing episode in Colorado where, in a mountaintop cabin complete with dog, he tried to set down his experiences.

"I lived at 9,300 feet and couldn't write the book," he says.

Brown came down from thet mountaintop to live in Denver and work in the Freds Harris campaign of 1972. When the caper ran its course, Brown and his two co-workers in the Harris office turned their political energies to a project which seemed equally unlikely - stopping the winter Olympics, which Colorado had completed for an won.

It was Brown's contention that the victory of promoters in landing the Olympics was a defeat for the people of the state. The anti-Olympics group received national publicity for its fight to protect Colorado's environment, but the campaign was shrewedly pitched to Coloradans as a waste of tax dollars: The voters rejected the Olympics, and Brown was on his way to a Colorado political career.

He ran in 1976 for state treasurer because, as he sees it in retrospect, "I was tired of working on ther people's campaigns." His opponent was a 58-year-old Republican incumbent, and Brown was denounced by the then GOP governor, John Vanderboff, as "an SDSer" (a reference to the Students for a Democratic Society) whose only credentials were "leading riots and radical parades and Gene McCarthy campaigns."

The banks contributed heavily to the incumbent's campaign. Brown said he would not take their contributions, though none was offered. he said that the state treasurer's officer was running a welfare compaign for the banks. One of Brown's campaign promises was that he would serve only a single term.

"I said that if I couldn't get done what I wanted to get done in four years you could take that as evidence of incompetency, and I meant it," Brown said. "I just don't believe in a permanent class of office-seekers."

Brown made the big Denver banks compete by bidding for the privilege of having the state's checking account, then $15 million. He gave carefully computed allowances based on loan-deposit ratios, student and small business loans, low-income housing loans and lending to family farms.

The bankers derisively called these factors "Brownie Points." Brown argued that it was a way of encouraging investment in deteriorating neighborhoods, where banks said that administrative cost of loans was high, and in agriculture, a capital poor industry in Colorado.

Brown's next project was even less to the liking of the banks. He published a Denver metropolitan edition of "The Bank Book: A Guide to Banking Services," which gave series of comparative tables on banking services and explanations of the types of accounts provided. The Colorado Bankers Association with a Brown questionnaire, so Brown sent people out to get the information.

The Denver booklet, printed free by the Oil, Chemical and Atomic Workers International Union and paid for by the Stern Fund and two other foundations, sells for $1.25, but is available free at various union halls, neighborhood organizations, schools and libraries.

Gradually, Brown has won the grudging respect of the bankers he opposes, even though the prevailing view is that he has carefully calculated his efforts for the maximum personal publicity.

But one Denver banker says of Brown: "Even though I wouldn't say this publicly, Brown has done 'us a favor in the long run with his insistence on competitive bidding and rate publication. The public is going to demand this sooner or later, and it's better that we do it before they demand it."

Brown is a political success because he is viewed as a man who keeps his commitments while remaining loyal to his friends. (He will not run, for instance, against embattled Gov. Richard D. Lamm, and has defended Lamm at a time many Democrats are turning away from him.) He is an effective user of the media. And he is a good manager who has chided liberals for thinking that good management is unimportant.

Brown's unassuming confidence seems to be typical of many of the antiwar group members who turned to local and state government. They behave as if standing up to the might of local economic power is an easy task after defying the weight and authority of the White House and the Pentagon.

The philosophical framework undergirding all of this activism is a ramshackle amalgam of socialism, Jeffersonian democracy and bedrock midwestern conservatism.

Brown favors state-owned banks and a publicly owned Federal Reserve Board, while at the same time deploring the power of the federal government. He is residully critical of the Defense Department, and he says, in the mildest of tones, that he "believes in a confiscatory tax system."

"My values are really from the right," says Brown. "They have to do with fairness and equity more than anything else, some sort of fundamental justice. The average person hasn't had that."

Brown shows this element of his intellectual heritage - he was at one time a libertarian right-winger of the Ayn Rand school - in his denunciation of that favorite conservative traget, the federal government.

"I really believe that the government that functions closest to home governs best," Brown says. "The people who have gone to Washington tend to think they know everything that's right and that we're all thieves, crooks or idiots."

Nevertheless, Brown remains attracted by Washington - and attractive to it. Last week there were reports that the Carter administration will ask him to serve as director of Action, the umbrella volunteer agency which includes the Peace Corps and VISTA.

Brown does not believe there is a great difference between what he stood for in the peace moratorium days and what he believes in now. He always has sought to build broad coalitions to deal with any issue that interests him, and in 1970 he advised the antiwar movement in an article in Washington Monthly: "The appeal must be made in such a way that Middle Americans will not ignore the substance of the argument because of an offensive style."

He made the same point more pithily this year when he explained to an Iowa reporter why he wore his business suit to the state capitol: "Never offend people with style when you can offend them with sunstance."

In offending with substance, Brown is reflecting the transferred energy of the peace movement, which now finds expression in a political alliance known by the unwieldy name of the Conference on Alternative State and local Public Policies. It had its first national conference last year in Austin and is to meet again this summer in Denver. The conference has published model legislation and held a series of meetings directed at solving specific regional or policy problems.

These one-time antiwar activists once raised the most fundamental questions about the international direction of their country. Now they have re-focused their attention to the communities and states in which they live.

"A few years ago I was out to save the world," says Brown. "Then I became interesed in the country and then the state I live in. Five years from now I may be trying to save my neighborhood and holding that up as the model for the world.