"Dear Mrs. Graham," the letter began.

"Our civics teacher . . . told us in civics class that it was unpatroitic for the newspaper to criticize our President. For our English class, I wrote an essay about Joseph Pulitzer . . . Could you please put you autograph on this envelope? This would be very good because your paper had so much to do just like Joseph Pulitzer."

The handwritten message was to Katharine Graham from Joseph M. Michaels, a youngster from Templeton, Calif.

In her handwritten reply, the chairman and president of The Washington Post Co. and publisher of The post newspaper, said: "Thank you for your nice letter and I am sending my autograph. . .Ask (your teacher) if he doesn't think the President was unpatriotic to do the things he had done?"

According to a subsequent reply from young Michaels, the teacher "just said Hmmm."

Another letter writer to The Post in recent months was John Ehrlichman. A former top aide in the White House of Richard M. Nixon, now serving time in a federal prison camp for his role in the Watergate conspiracy, Ehrlichman wrote from jail to Post executive editor Benjamin C. Bradlee. He complained about the condition of Washington Posts he was receiving by mail at his camp in Safford, Ariz., and threatened to change to The New York Times.

"There's a man who didn't understand, who hated us, who was at war with us, but he's taking us in jail. . .in Arizona," Graham said.

The letters cited above are just two of hundreds mailed each day to The Washington Post, and Graham said they show "that your credibility is there and your interest is there and your vitality is there . . . and usually if you have the editorial product or vitality that we have, it also gets the readership that you need and the advertising base that you need."

Vitality, there is, in the pages of The Post. The morning newspaper, which will complete 100 years of daily publication next Dec. 5, was described by Time magazine earlier this year as one of the "two best" dailies in America along with The New York Times - "and they far excel the rest," said Time.

While the Washington newspaper "often overplays its own stories" and "relies a great deal on news services . . . The Post is a high-wire act . . . In a one-industry town, the Post excels in its reporting of Congress and the bureaucracies . . . Overall the Post is better written (than the Times) with a prevading sense of self deprecating irony," the magazine added.

Such accolades have been commonplace ever since The Post uncovered the Watergate scandal - the political machinations of Nixon and his men, including Ehrlichman, which forced a President to resign in disgrace for the first time in American history.

The Pulitzer Prize-winning journalistic expose by the federal city's dominant newspaper subsequently was chronicled in the best-selling book and movie, "All the President's Men."

The paper's stature and local dominance are relatively young phenomena. Twenty-five years ago, the Washington market was dominated by the Washington Star, in both advertising volume and circulation. While The Post always had a small national following from its inception, recognition of its daily news report as among the best in the newspaper industry surfaced only gradually.

The story of the modern Washington Post Co. and its trend-setting newspaper of recent years, in fact, began during the Depression. Financier Eugene Meyer purchased the newspaper in a 1933 bankruptcy auction for $825, 000 and declared:

"The newspaper's duty is to its readers, and the public at large, and not to the private interests of its owner . . . In the pursuit of truth, the newspaper shall be prepared to make sacrifice of its material fortunes, if such a course be necessary for the public good."

Meyer himself had emphasixed the belief that a truly independent newspaper requires a strong economic base of profitability. Post District Line columnist Bill Gold recently recalled a conversation with Meyer, as follows:

"Don't misunderstand, Meyer cautioned. Making money has its importance. It shouldn't be dominant, but neither should it be deemed unimportant by a rich owner, because owners come and go. Life is finite. New people take over management, and the old owner's money is no longer behind them. For an institution to a maintain its independence and feel free to do what is right rather than what is expedient, it needs to earn enough public support to become financially independent, too."

Today, Meyer's daughter is chief executive not only of The Post but also of a variety of communications businesses that have been acquired by the newspaper firm since the late 1940s. And Katharine Meyer Graham has devoted a good deal of her time since taking over in 1963 to improving the company's economic strength - thus to preserve the journalistic integrity of the firm's newspaper, magazine and broadcasting properties.

In an interview, Graham said she "takes a lot of pride" in the company's recent records of profitability and journalistic excellence. "I think that, in fact, a well run company can and should do both sides well. And I feel that we have dedicated ourselves to an participatory sports reporting now included in Thursday's Sports II, which will cease to be a separate section.

The Post also is expanding its business and financial coverage - with 30 extra columns a week for the business news section and three new reporters, starting in September.

Potomac, the Sunday magazine, will get a new name - The Washington Post Magazine - starting Sept. 1. In addition, the magazine will be stitched for the first time and produced with a higher-quality printing process.While some new features will be added, including a new "Front Page People" column, Bradlee said the publication will "maintain its local character and flavor."

The Post has opened a new bureau in Houston, it third in the nation (others are in Los Angeles and New York). One item dropped from the newspaper in a gossip column, which appeared in the Style section.

As newspapers move into a new era of computer-based technology, which will remove typewriters from reporters' desks at the Post and other papers, "We're all going to have to work like hell to keep some personal warmth in the approach to journalism," Bradlee warned.

And if newspapers can produce their product at less cost, he said, that means "more money can be contributed to product improvement." Bradlee said papers in general, and the Post in particular, have got to get later news to readers through a speedup of the production process. "We're still turning out 60,000-plus papers each night with news that was over before the 6 o'clock news was over."

As a general rule, Bradlee concluded, "we ought to try and simplify and explain and help people cope with a life that is getting more difficult. Those who do it best will succeed."