"The letter was a declaration of independence," Sullivan said, adding that the message to potential shareholders is, "We dare you to invest in us."

But Sullivan also said the letter reminded him a bit of Ben & Jerry's, the Vermont ice cream company that eventually stumbled after operating unconventionally for years. He said Google's "ivory tower" mentality means that it can stumble and seem out of touch, as it did recently with the introduction of Gmail, its free e-mail service with ads that was attacked by privacy advocates.

"They think nobody will have a problem since they think they are this lovely company out to do good," Sullivan said. "The real crunch will happen to them when the money is not rolling in."

While Google derives 95 percent of its revenue from ads, Brin and Page said Google will not accept payment in return for a promise to include Web sites in online searches. (The ads appear to the right of search results.)

"Google users trust our systems to help them with important decisions: medical, financial and many others," the letter said. "We will live up to our 'Don't Be Evil' principle by keeping user trust and not accepting payment for search results."

Yahoo Inc., which the was identified as Google's biggest competitor, says it allows companies to pay for inclusion in a search but does not guarantee they will appear in search results.

Brin and Page also emphasized the approach that has enabled them to attract and retain highly motivated computer scientists and others -- something that may become more difficult once many employees find themselves millionaires, at least on paper, after the public offering.

"Talented people are attracted to Google because we empower them to change the world; Google has large computational resources and distribution that enables individuals to make a difference," the letter said.

Among other things, they encourage employees to spend 20 percent of their work week pursuing their own ideas rather than assigned projects. The letter said Google's electronic news alerts were created this way: "Most risky projects fizzle, often teaching us something. Others succeed and become attractive businesses."

Andy Beal, vice president of Websourced Inc. -- a firm that advises companies on how to advertise online -- said a quick survey of 100 customers revealed that 27 percent doubted Google could stick to the founders' principles after going public, while 20 percent thought they could. The rest were unsure.

"They are not prepared for the pressures of their shareholders and from Wall Street," Beal said. "At some point, the two sides are going to clash, and something has to give."