Esalen revisited: influential experiment from an experimental era; The Upstart Spring: Esalen and the American Awakening, by Walter Truett Anderson. Reading, Mass.: Addison-Wesley. 339 pp. $11.95.

Since its appearance 20 years ago, the ''human potential'' movement has influenced many aspects of modern thinking and doing. Directly and indirectly, it has altered such areas as counseling, business, the ministry, and social trends.

Many of the principles and philosophies Thomas Peters and Robert Waterman found practiced by the most successful American businesses (and reported in their best seller, ''The Search for Excellence'') were verbalized and made accessible to the general public by Carl Rogers, Abraham Maslow, and others back in the early '60s.

We need to treat each other better, they said - pay attention, listen to one another. We need to recognize that people gravitate toward warmth and intelligence. In man, they said, there is something higher than the animal.

The human potential movement was an often serendipitous, often awkward search for just what that something was.

It would be difficult to pin down exactly why this ''movement'' caught fire in California and then spread (in diluted form) to colleges, churches, and management consulting firms nationwide.

At one level it was a reaction to the spiritual nullity of a postwar society (soon to be labeled ''secular'') occupied with the perfecting of goods and services. At another level, ''human potential'' countered the often man-belittling intellectual currents set in motion by Darwin and Freud. At the purely geographic level, the movement was ignited by the restless frontier energy bottled up on the nation's West Coast, its last physical frontier.

And then, the atmosphere was, well, more relaxed. What you could only think about in New York, you could do in California.

Unfortunately, in the popular mind every new West Coast development was apt to be lumped in the same category with hippies and hot tubs, and the human potential movement was no exception. Its critics, and there were many, could accept the idea of ''human potential'' so long as the soul-searching was being done mainly by the fringe element - artists, rich eccentrics.

But in a 1968 article in The Nation, Theodore Roszack offered a perspective that helped balance some of the criticism: ''Let 'ordinary' people once get wind of the importance of self-knowledge and personal autonomy, and they are all too likely to think that idea has something to do with taking themselves very seriously, brooding over their tastes and motivations, delving into their experience, rebelliously asserting their peculiarities - in short, becoming . . . what others will denounce as . . . 'self-absorbed.' ''

Roszack recently told the Monitor, ''If there hadn't been something called the 'human potential' movement in the '60s, a different name would have been invented.''

In some ways, the flagship of the movement was a little remodeled tourist resort called Esalen, located above a series of underground hot springs on California's Big Sur coastline. In ''The Upstart Spring,'' Walter Truett Anderson, a social and political scientist from San Francisco, takes a close look at Esalen and the people who went there to talk, dance, explore, explain, encounter, play, study, escape in the '60s.

Yes, it had a hot tub. No, it wasn't all a joke, Anderson assures us in his well-written book.

''The Upstart Spring'' takes us back to the founding of Esalen by Michael Murphy and Richard Price, two young men who had been inspired by the ideas about human potentialities put forth by Aldous Huxley.

Murphy, who in the 1950s had been a pre-med student and ''undergraduate atheist'' at Stanford University, underwent a dramatic change after he blundered into a lecture on the Vedas, the ancient Hindu scriptures, given by Frederich Spiegelburg (an associate of Paul Tillich and Martin Heidegger).

After a disillusioning visit to India, Murphy came back to the U.S., met Price, discovered a community of people interested in new ideas, and created Esalen as a place to discuss them. The two recruited such thinkers as Tillich, Huxley, Arnold Toynbee, Gregory Bateson, to speak on the issues of the day - including social theory, existentialism, subjectivity, anthropology, and bridges between Eastern and Western cultures.

As the enterprise became more successful, Murphy and Price became more daring and, true to the spirit of the '60s, starting workshops and programs less academically oriented and aimed more at offering people a direct experience, a place to ''get in touch.''

Maslow and Rollo May came. Fritz Perls made Esalen a home base both for himself and his own brand of Gestalt psychology (and Anderson criticizes both).

True, as Esalen became popular and the '60s became wilder, in many ways Esalen became less serious. People took their clothes off. They used drugs (though without the sanction of the people running Esalen). Programs failed. Anderson doesn't spare criticism.

But, as Anderson shows, much of this was a phase. Beneath the surface the serious intentions remained intact, albeit in California style.

Today, a more mature Esalen holds conferences on physics, governance, and world politics, along with less formal attractions such as ''sensory awakening'' and massage therapy.

Today there is no real human potential movement as there was 20 years ago. Some of the ideas filtered into the mainstream culture, and some are found in humanistic psychology, holistic health, and various quasi-religious and ''positive thinking'' schools of thought.

Perhaps one of the key points of the book is that Esalen was an experiment in an experimental decade. Many of the questions broached there regarding the role of the human spirit in an age of mechanization are still pertinent, as Anderson points out.

The author, who has dipped into Esalen offerings himself from time to time, nevertheless maintains a healthy distance and skepticism throughout.

The result is the first responsible account of an important, uniquely American happening - worthwhile reading for anyone who wants to piece together the social undercurrents of the '60s.

Anderson writes about Esalen at the end of the book: ''It has produced much joy, much peace . . . some despair, a lot of excitement, a good measure of foolishness, and no small amount of hubris. It is a mixed blessing, but a blessing nonetheless.''