DALLAS, Texas -- It has always been something of a mystery to Harvard's resident population exactly what Harvard's president says to Harvard alumni that makes giving vast sums of money to the University such a cathartic experience.

Is it the depiction of desperate financial straits, of the Good Old Days slipping away but still salvageable, or of grand visions for the future? It is really a little of each.

The subtlety of this technique was demonstrated by President Bok recently before 200 Harvard types gathered here to take advantage of what the director of the Harvard Parents Program billed as an opportunity "of learning all that is current at Harvard such as co-residency and curriculum reform."

During a two-day sojourn to Houston and Dallas, Bok inspired typically effervescent introductions before audiences composed of alumni, parents and spatterings of high school seniors eager to score brownie points with the Cambridge aides who accompany Bok on these journeys. (It is just as important, no doubt, that the aides be there to fill in equally eager alumni on the tax implications of large contributions.)

In Dallas, Stanley Marcus, the Marcus half of Neiman-Marcus and a former Overseer, noted that he has known four presidents of Harvard. Of the three, Lowell was an egoist, Conant a brilliant scientist, and Pusey a great generalist. But Bok, Marcus said, aside from being an accredited legalist, is the only humanist among the four.

Marcus must have caught the President's address in Houston the previous night to come up with that judgment. In fact, the thrust of Bok's remarks was that in the face of new technology in society and demands for relevance in American education, colleges and universities must not lose sight of the pursuit of "pure knowledge."

Bok has been trying since his tenure began to turn attention to educational reform. His focus here on nostalgia for the bygone days when students and faculty united in a quest for intellectual breadth was something different, however.

The President addressed himself to two periods in Harvard's development and in the development of universities generally -- the mid-thirties and the present. He pointed up crucial differences between the two; referring to the student unrest of the sixties and early seventies as "bizarre troubles," he said that these troubles were "exotic ripples on the surface which mask more profound changes underneath."

Striking themes familiar to anyone who has been in Cambridge recently, Bok identified current pressures on Harvard as these:

* In the past two decades there has grown up a new view of universities as a "vital national resource." Correspondingly, there has been a tremendous influx of Federal aid which, when now withdrawn, threatens basic research and teaching programs.

* There has been a dramatic increase in reliance of government on academia as a talent pool. Howard Aiken and Felix Frankfurter were precursors of this increased reliance 35 years ago. Now there is a wide recognition, Bok said, of "how central advanced education is to everything in society." The emphasis on academics in public life means that "professors often have opportunities to work outside the University that did not exist 35 years ago."

* There have been manifold problems associated with the internal growth of universities. At Harvard, Bok told the alumni, it has been necessary "to establish a large and more complex bureaucracy which is more cumbersome than before." This structure, he said, "is irritating and unfortunate to many of us who feel academic institutions should work without a bureaucracy, but we must accept it."

The conclusion Bok drew about the effect of these pressures is not so familiar as the pressures themselves. His premise was that "despite financial difficulties, the really scarce commodity in Cambridge is time, not money."

Bok reasoned that the enormous emphasis put on Federal funding for research in science and medicine has drawn time away from libraries, teaching, and basic research. In turn, this has had "a fundamental influence on the kind of activity that goes on on the Harvard campus now (as opposed to) 35 years ago."

A real danger, then, is not financial restriction -- Bok said that unless Congressional action imposes new restrictions, the financial situation is well in hand -- or irrelevance in the curriculum; the danger, Bok said, is "that universities such as Harvard will become too relevant, too preoccupied with the problems around them."