Boston — It was not something expected from your average rock star. Graham Nash of ''Crosby, Stills & Nash'' (CSN) - the legendary trio whose creamy vocals wowed audiences 15 years earlier - stepped out of his dressing trailer to greet a horde of anxious fans. He had just opened another sold-out United States tour on the Boston Common and, for 45 minutes, patiently signed autographs and answered questions. Finally, he turned, obviously exhausted, to go back into his trailer.
Just at that moment a young handicapped man called to him. Without a second thought, Nash went over to the man and put his arm around him; the two talked for several minutes - to the young man's delight.
That is the kind of person Nash is.
The next day a barefooted Nash sat in a shady alcove at hotel poolside and talked about why he continues to love writing and playing music so much. ''My passion is alive,'' he says, his northern English accent still intact. ''If you can keep that alive, you can grow. If you get squashed, flattened, made gray, it's difficult.''
No doubt part of the reason the group still plays together is the remarkable staying power of the music. The popularity of their songs today was more than hinted at when - on the Common the night before - virtually the entire audience (many of whom were toddlers 15 years ago) rose to its feet to sing the familiar lyrics to the ebullient CSN anthem ''Teach Your Children,'' a song Nash authored in 1969.
That year, following the release of their first album, CSN became an instant success. Not since the Beatles had one group risen so swiftly.
Part of the reason was that CSN spoke (sang) for a generation breaking with tradition, backpacking across America, ''finding itself.''
More than anything, they represented an outlook. Ten years earlier Chuck Berry's bluesy rock-and-roll was wonderful to dance to. But Berry didn't try to invest his music with ''meaning,'' as CSN did.
I asked Nash about this. In the late '60s and early '70s, the Fifth Dimension was singing about the age of Aquarius, and Nash's own music talked about the ''age of truth'' arriving. Looking back, have things turned out the way he had expected 15 years ago?
''Not at all,'' he smiles. ''I thought it would be sunnier, brighter. My utopian dreams have been tarnished slightly. But not entirely. I'm a hopeful person. A lot of people have forgotten our dreams back then. A lot of people have given up. Not me.'' As if to corroborate, he adds that CSN toured with a voter registration booth. ''We registered 300 people last night!''
Although their music has often been ''political'' or ''social,'' just as often it has broken away to a gentler, happier sound, as in ''Suite Judy Blue Eyes'': ''Chestnut brown canary/Ruby-throated sparrow/Sing the song!/Don't be long!/Thrill me to the marrow!''
Neither has CSN been strangers to the electric guitar, especially when the mercurial Neil Young added his sharp licks.
But the group's legacy has been one of acoustic music - a sound that spawned a whole school of what is today called ''soft rock,'' including popular groups such as ''The Eagles'' and ''America.''
Former Eagle Glenn Frey remembers hearing the first CSN album in 1969: ''The sound . . . was like this massive ahhhhh! . . . coming from the heartland . . . everyone . . . wished they could sing like those guys.''
About certain dehumanizing aspects of the current punk rock trend, Nash says, ''When we were kids listening to music in our homes, it didn't seem the end of the world was possible. But the world is different today. Ten years ago you could take time to look into a girl's eyes and get loon-June and feel good. Today, many kids just don't care.''
At the same time, Nash feels kids to day are ''faster, hipper, brighter, more direct than we or our parents were.'' But he says he feels there is a ''great frustration'' in today's youth. ''They don't know where to get an answer. Their government often doesn't work. Their family doesn't work . . . they can't work it out with mother and father. So they'll go to drugs, to their friends, to the gangs. They rebel.'' And this, he says, is reflected in their music.
Nash's answer to these problems is for people to become more ''family oriented.'' ''The destruction of the family has been a bad, bad thing. I'd like to take stock . . . have the family unit reevaluated, reestablished.''
What does he teach his own three children?
Nash blushes. ''I don't always know! There's no instruction booklet that comes tied to their toe! But I do teach them to be gentle and inquisitive. I also let them know that the world is not bigger than they are. That it will not defeat them.''
Nash, born in England during World War II (in an evacuation hospital hidden from the German Luftwaffe), spent his boyhood in the city of Manchester. On his first day of school, at the age of 5, he sat next to Allen Clarke - a lad no one else would sit near. As it turned out, Clarke and Nash became friends, discovered ''skiffle'' (a crude '50s British-cum-Elvis Presley rock-and-roll) in their teens, and later formed ''The Hollies,'' an extremely successful group patterned after (of course) the Beatles. The two stuck together until late 1968, when Nash broke away to join Stills, from Buffalo Springfield, and Crosby, from The Byrds.
Although Nash still feels his roots are in England, he recently became a US citizen and feels ''so appreciative'' to be ''here in this country.'' ''When I became an American citizen, I meant it. When I was singing 'The Star-Spangled Banner' and crying, I meant it. I love this country. I feel there's no limit to what I can do here.''
Nash continues to flavor his music with his favorite issues. ''Barrel of Pain ,'' for instance, was written about dumping radioactive waste off San Francisco Bay.
Nash confides that his recent song ''Wasted on the Way,'' from the ''Daylight Again'' album, speaks to an issue that has often troubled him: why Crosby, Stills & Nash did not record more often. ''It (the song) was from a post card I wrote David (Crosby) and Stephen (Stills) to say, 'Hey, listen, 4 albums in 15 years? A bit of a joke, isn't this? Can't we come together for longer periods? Haven't we wasted too much time already, arguing? Haven't we hurt our responsibility? Have we not wasted a lot of love?' ''