"Why is Cambridge, Mass., famous these days?" Jim Schlesinger has been asking with a grin. "Because, the President's energy adviser, who just happens to be a Harvard man, replies, "it's the home of Tip O'Neill, the greatest Speaker of the House in the modern era."

That praise expresses an admiration verging on reverence that it widely felt for O'Neill's performance in managing the President's energy program. Whatever the merits of the bill, and whatever form it finally takes, getting the total package through committee and onto the floor of the House in less than a hundred days was the kind of legislative feat that has not been seen since the civil-rights bill of 1964.

The package that the President presented on April 20 was intrinsically complex and controversial. In included continuing regulation of natural-gas prices, and taxes on gasoline, big cars, oil producers and users of natural gas for fuel.

These proposals, by pitting regional interests against each other, lent themselves to the instinctive congressional habit of logrolling - trading protection against taxes on cars, for example, for protection against taxes on oil and gas. In the past that kind of accommodation had killed all efforts to work out a comprehensive energy package.

O'Neill brought the whole package onto the floor intact on his Aug. 1 target date by a variety of devices. He set fixed deadlines and pushed the leaders of the Commerce and Ways and Means committees to finish their work by mid-June. He established an ad hoc Energy Committee to maintain the general public interest against the pro-consumer bias of the Commerce Committee and the pro-business bias of Ways and Means. He kept committee chairmen and regional whips constantly informed. He encouraged compromise - notably to beat back the deregulation of natural gas.

These devices wouldn't have worked except for a variety of other conditions. For one thing, two great barons on the Democratic side - Chairman Wilbur Mills of Ways and Means and Chairman Wayne Hays of the Administration Committee - are out of the House. For another, chance has given O'Neill three strong lieutenants, Majority Leader James Wright (Tex.), Majority Whip John Brademas (Ind.) and on the Rules Committee that demon legislator Richard Bolling (Mo.).

O'Neill himself, moreover, has been a master of the old politics of getting along by going along. As Majority Whip from 1971 to 1973 and as Majority Leader from 1973 until last January, he was tireless in making speeches and helping raise funds for other members.

Those favors did him little good with the freshman and sophomore classes, who compose about half of the Democratic caucus. But O'Neill had standing with them because he broke from the Democratic majority early on Vietnam and was the powerhouse behind the impeachment hearings on Richard Nixon.

More recently, O'Neill led the way in two reforms dear to the younger members. He put across the rule by which committee members are now elected instead of automatically reaching the top through seniority. He also sponsored the measure that has required on-the-record votes on all major issues.

Finally, there are personal qualities, easier to feel than to describe. O'Neill is not only a genial giant with an irrepressible store of banter and a love of the House. He also has the broadest shoulders in town. It is practically impossible to be with him and not tell him your troubles. It is even harder to come away without the sense of having been supported.

As Speaker, O'Neill has put these talents to work for the whole House. He stood up against the initial instinct of the Carter administration to write off the Congress in favor of the country. He pushed through the pay raise so essential to many members. He also put through a tough ethics code that builds a barrier against corruption.

Years ago I asked O'Neill about the aspirations of a rival. "The House will never make him Speaker," O'Neill said confidently. "The House won't give the job to a man without class."

Maybe and maybe not. But in O'Neill the House has found not only a leader but also a champion. He has arrested the demoralization of the past few years. He gives the members a feeling of pride, a little touch of class.