"TAKE OFF your shoes and socks and leave them in the hall," the sign read. Inside, in the assembly hall of the Christ Church parish house, a tall man with gray hair was blowing up an enormous white balloon--at least six feet in diameter--with an air pump. His name was Ted Moynihan, and he wore black leotards.

He tied the balloon in a knot and began bounding, around the room, knocking the balloon up into the air with his head. Around him were a couple of small children, playing with balloons of their own, and several young men and women, also in leotards. While Ted bounced the enormous balloon off his head, the young dancers--members of the Boston Conservatory Dance Group--did sit ups and stretches. In the corner of the room near the door, a group of about 50 students, having taken off their shoes and socks, looked on in bewilderment.

With one ferocious swat of his head, Ted sent the balloon up to the ceiling, where it hit against a light and burst. Ted turned to his audience and coolly said, "All right, let's begin." He led the students, about two thirds of whom were girls, out onto the floor of the assembly room, a little larger than a basketball court. He spaced them out, dimmed the lights, and said, "We'll start with breathing exercise."

For about five minutes, everybody breathed -- standing on their tiptoes with their arms held high over their heads when they inhaled, collapsing down to the floor when they exhaled. Then, with Ted leading the way, the group formed into a circle and began to march around the room, alternately very stiff and very relaxed. Over the loud-speaker, a minuette began to play--and at that point, the first performance of Cambridge's Free Dance Theatre began in earnest.

To the different kinds of music that were played, the dancers became, in order, English nobles, Spanish castancttas, and African warriors. Suddenly the music stopped, the lights went completely out, and Ted's voice echoed, "Reach out and find someone to hold onto."

With remarkable ease, people did--and, as Sergeant Pepper began to play, they huddled their way into groups of eight or ten, lying on the floor, intertwining arms and necks and elbows and heads, and gently moaning. Then the lights were back on, and Ted was announcing that the dancers from Boston Conservatory wanted to form "discussion groups" and that students should cluster around them.

ONE OF THE dancers, a slender girl with short blond hair, gathered eight students around her--four and four--and began by saying, "We're going to use our bodies to express emotions." She asked them to choose an emotion. "Happiness," one of the boys suggested: so for a while they were happy, then thankful, then obsessed, then lonely, and then sad. "I can't seem to do this," said a tall boy in corduroy pants and a bright polka dot shirt. "There isn't enough space. I wish we were on a football field." The leader of the group tried to help him, while the others paired off to express themselves.

Some time later, when most of the groups had degenerated back into the love mounds out of which they had formed, Ted turned on the lights, announced the beginning of the "free dance," turned off the lights, and turned on a colored strobe. Some fast music began to play. In the strobe, to the music, worn out and relaxed by the exercises of the first half of the evening, everybody danced. They danced happily, passionately, playfully, romantically, with Ted leading them all. After an hour and a half, many were still dancing, and as one group of students turned to go, Ted waved to them and shouted, "By May we'll have 5000 people dancing on the Cambridge Common." He turned back to the girl he was with and went on dancing.