ON A LARGE COLLEGE CAMPUS there are few universals in a student body's collective consciousness. To prove this fact figure not the number of ways you can call start a conversation with an undergraduate you've never met. Counting generously, there are only five opening lines guaranteed to mean something to any Harvard student.

1. "Some weather we're having huh?"

2. "What kind of course are you taking anyway?"

3. "So tell me about your vacation."

4. "Hey how's the inhaling and exhaling going?"

5. "Can you believe what's happening to Uncle Duke in Hollywood?"

That was in 1982 this is 1983, and the count has dropped to four. It's hard to find the right way to think about Garry Trudeau's decision not to draw. "Doonesbury" for the net three semesters. This generation of college students has no equivalent cultural tragedy to compare it to we weren't going to the movies when Shirley Temple turned into a teenager. We weren't reading magazines when Look and the old Lifefolded, we weren't going to rock concerts when the Beatles broke up.

But it's easier to understand the passing of phenomena like these, which are vulnerable to the depredations of time or the stresses of close collaboration. All audiences know that their best-loved group efforts depend on a cooperation too fragile to last forever.

Garry Trudeau had no one to break up with. And for all the sentence he may have weathered, his characters were reassuringly age-proof, day after day. What could have cut them short?

There is also a difference in magnitude that makes the disappearance of :Doonesbury" more unsettling than any analogous loss of earlier years must have been. When an author stops writing, an actor dies a radio or a T.V. show goes off the air, a fan's daily schedule is significantly altered. There's no longer a regular afternoon set aside for the new Agatha Christie, no longer a weekly hour and a half for the Belushi Ackroyd Saturday Night Live. These are giant gaps in the landscape and to compensate for them, you shift your perspective and learn to work around them.

Losing "Doonesbury" is different. The 20-second pause for the morning's stop was not an item on anyone's schedule it was part of the metabolism. There was a difference between days when you read "Doonesbury" and days when you didn't just like the difference between days when the digestive system functions well and the days when it doesn't. The chuckle that came at the fourth-frame punchline could suffuse the whole day: you'd repeat the words over lunch and find yourself smiling at them over dinner. How can you compensate for that, short of synthesizing some kind of Artificial Doonesbury in section?

Bleak times lie ahead, For the time being. Crimson readers can string themselves along on artificial support, but soon our supply will run out. The methadone of "Bloom County" and "Funky Winkerbean" may alleviate the ordeal on some mornings: flashbacks from old "Doonesbury" collections may bring relief on others.

Otherwise let us take courage and remind ourselves that trials like these strengthen character in the end; let us silence the sinister skeptics among us who suggest that this is really curtains forever for "Doonesbury" --that Trudeau's line about a "vacation" is a ploy to ease readers into the more terrible truth--and finally, let us fantasize. Maybe Garry Trudeau still draws a strip every day and puts it away in a drawer. Maybe in 1984 at the end of his sabbatical, he'll set them all free--more than 500 brand new sequences, more than 2000 new frames-- and we'll all put down our books, walk out of our classes and spend the day with our new treasures, with our old friends, with Zonker. Mark. B D,. Joanie Rick, Uncle Duke, Rev. Sloan Huney, Mr. Slackmeyer, Phred, Bernie, J.J., Boopsie Zeke, Lacey and Dick Davenport, Roland B. Hedley Jr., Jimmy and jenny Thudpucker. Ellie. Howard, Riley, Woody, Lava-Lava, Dr. Dan Asher, kirby, Barney, Weinburger, Duane, Ginny, Clyde, Nicole and Mike Doonesbury.