THERE WAS a time - as a very young man with peace in my soul and faith in a just future - when I could play tennis happily at Rose Park or Montrose or Turkey Thicket or some other public court. I could concentrate through the din of traffic and basketball and portable radios.

What matter that a woman in high-heeled shoes, cigarette in one hand and racket hanging limply from the other, might wander onto my court as I prepared to smash.

Or that the net was so full of holes that your opponent's lousy shot might cost him the point and you the ability to reproduce.

Or that on the next court one man was sitting on another's chest, hands about his neck, screaming, "I've been here three hours. It's my court, it's my court!"

But I am older now - a junior vet - and lacking the milk of human kindness. Children gaily riding bikes on wet clay courts cause a rumbling in my stomach. I want to break their spokes.

Hours of waiting for a court, watching people who can't play tennis, causes a seething in my brain and renders me incapable of hitting a backhand down the line when I finally get to play. I want tennis players to be licensed and bad ones sent away. Democracy for the elite is my motto.

I consulted with learned men about this radical change in my tolerance level and was referred to the famous public courts counselor Dr. Willie Flatcher, who unfortunately can only be seen when one is losing one's mind.

Dr. Flatcher, a long-time opponent, is in part responsible for my problem, so he agreed to treat me gratis. Unfortunately he requires that you play with him as part of the therapy.

He set a time at a public park and when I arrived the courts were empty. When he got there 40 minutes late, the courts were full and the waiting time was two hours.

He watched closely to see if this disturbed me, then suggested another park.

Those courts were empty, but as we raced on, a man approached on a little tractor and said the courts were closed for maintenance. They were of course in perfect shape.

It was the start of a three-day weekend and I asked calmly if they would be open soon. He said they would be ready Tuesday. Flatcher was impressed with the guttered sound I was able to make.

flatcher found another park but we were soon run off by the Future Senior Citizens of Greater Glebe Gulch, who explained that they held their mixed-doubles tournament there every year at just that moment and had reserved all 18 courts. Their teaching pro was a gentleman who had once asked me to play and was ahead 5-2 in the first set before I discovered his weakness. If the ball was not close to the line he couldn't automatically call it out.

At the next park, the clay courts were wet from a sudden shower but a fellow about 5 feet 2 and 300 pounds was playing anyway. At each step he [WORD ILLEGIBLE] about two inches into the court and he finally quit, complaining about the bad [WORD ILLEGIBLE]

The sun was by that time baking the charts so that his hoof prints would last until the next monsoon.

We finally found a court about an hour before sundown and waited our turns. There were two courts with two young men on one and two middle-aged women on the other.

I checked my watch and an hour later, as the light began to fail, politely asked the men if they were through.

"Oh, no," said one, "we'll be through in about 20 minutes."

"Off," I screamed, and they left, grumbling about poor sports.

As I took off my racket cover, the two women moved into our court and continued their match.

"Excuse me," I said, "but this is our court."

"No, it's mine , mine, mine and you're not going to take it away," screamed one woman. "Mine, mine, mine." She sat down in the middle.

Flatcher grinned as we moved onto the other court, surrendering.

It had been carefully repaired by the D.C. Recreation Dept. so that the ball would bounce at any of three different speeds, depending on the patch on which it landed.

Flatcher, who is lefthanded, would change his serve depending on the patch he was aiming for. His flat serve on the slick conrete skidded away with almost no bounce. His twist serve onto the rough asphalt kicked over my head.

He had insisted that we use his balls and he used a worn one for flat serves and a fuzzy one for spin. The third ball was fead and he mixed it in for effect.

The net, which was an inch too high and couldn't be adjusted because the crank was rusted solid, caught my best shots in the tape.

Flatcher hit a lob with the dead ball and the court was so cleverly aligned that even at sunset the glare was directly in my eyes.

I let the ball drop and would have called it out except that the base line was painted six inches wide and faded out into decreasing spatters. I didn't know if the spatters were in or out.

I screamed and threw my racket and Dr. Flatcher smiled and pronounced me saved.

"There is no cure for creeping public courts syndrome," he said. "My records show that you once belonged to a private tennis club in California and that you have played at the estates of men who have not one but two courts in their yards. Tennis etiquette. Proper shoes. New balls. Rules. There is only one thing you can do."

I took his advice and joined a private tennis club. It has cost me exactly $1,000 so far and the courts haven't been built yet.

But I'm much happier.

Dr. Flatcher assures me that paying for the private club is the real therapy. Actually playing there can be damaging, he warns, since the private club is likely to be just like a public one.