What's next?

Marshall McLuhan once said, ''We march backwards into the future.'' He might just as well have said we go into the future looking sideways; which is forward if you happen to be a fiddler crab.

This kind of speculative philosophy about the future has more the profundity of Bob Hope than Albert Einstein. Any statement, having contrarity of meaning, seems edged with brilliance until you hear some shirtless person say it while waiting in line at the post office.

How are we supposed to go into the future? Marching forward with stern resolve? Not into my future we don't.

My future is there only to look forward to. Not to arrive in.

I remember as a child when I was promised a trip to the circus. For several days I thought I was ''looking forward'' to it but I didn't really picture the circus I was about to go to. I pictured the one I had been to last year, mentally transporting it into the future. Since all circuses are alike, my ''looking forward'' was just a rerun of the past, except that the tickets cost more.

We can't actually see into the future. In fact, we can see only what we are already seeing. So naturally we would meet the future looking at what we have been looking at. This doesn't mean forward. At least not in my case. Half the time I am looking backward at someone who just went by.

All of which brings me to Spoonbill Benson, a boy who sat in back of me in my high school civics class. The future never seemed the same after I got to know Spoonbill Benson.

Spoonbill wasn't his real name. Benson was; but not Spoonbill. I can't remember Spoonbill Benson's real first name. Everyone in those days had a nickname, and Spoonbill simply described how he looked.

Nicknames were accepted more than they are today. Even girls had nicknames. One girl was known as Bareknees Beatty. This isn't the best example, for although her daily costume revealed beautiful bare knees, her name was actually Bernice. So it was a name with a double-whammy.

The thing that first attracted me to Spoonbill Benson was that he seldom, if ever, paid to go to the movies. It wasn't a case of climbing through a window. He simply walked into the movie backward and everyone thought he was coming out.

This is sort of a primary example of the way Spoony looked at things. In this case, you could consider seeing the movie as his future and his walking backward as his means of arrival. I can vouch for this performance, having watched him on at least one occasion. At one time I understand he actually spoke to the ticket taker as he went backing into the lobby, saying, ''I sure enjoyed the picture.''

We have a bird that does this when we are eating breakfast on our backyard wharf. We purposely drop items from our plates and if they fall very close to us , the bird does not approach the food bravely looking forward, but, like Spoonbill Benson going into the theater, unconcernedly hops backward up to the food. In the bird world this evidently conveys the idea he is not courting any future danger but is on his way home.

This doesn't prove much about marching backward into the future, but it shows birds aren't so much smarter than people.

Spoony Benson's theories were not limited to walking backward. Sitting behind a chocolate malted down at the drugstore, a far-off expression in his eyes, he would relinquish his straw carefully and say, ''If we started traveling faster than the speed of light, we could, in time, overtake a view of our past while moving into the so-called future. . . .''

Whenever he said something like this, my date would sigh and then give me a look as if I were something on the end of a fishhook.

''All molecules, or atoms, travel at different speeds,'' he argued. ''Therefore you are never exactly where you think you are. Or rather, you are only where you think you are.''

Once at a class picnic he said, ''Molecules are always flying off the edge of things. We are constantly losing molecules. It is also possible we pick up other flying molecules.''

That was when I turned to my date and said, ''I'm picking up some of your molecules, baby.'' But she only answered, ''Oh, keep still. You're flying all apart.''

Spoony would sit in the bleachers while the rest of us played baseball, filling a notebook with equations. At the end he would say, triumphantly, ''Aha! Just as I thought!''

''Do you realize,'' he whispered to me one afternoon in study hall, ''you are always putting yourself inside your own thoughts? After this bit of information sank in, he continued, ''How far do you walk to school and how long does it take?''

''Three miles,'' I said. ''It takes forty minutes.''

''Right now you can think of that whole three miles completely. You can see yourself traversing it instantly.'' He was always using words like ''traversing'' and suggesting that we could walk through a wall if we could keep the atoms from bumping one another. There was, he explained, really a lot of space between them.

Everyone should have a Spoonbill Benson in his life. Since we never arrive at a future moment and therefore the future really can't exist to go forward into, it is nice to have a Spoonbill Benson around, looking in every direction at once.

''The only physical proof of eternity we have,'' Spoony said the last time I remember seeing him, ''is that there is always a next moment. We simply live in an expanding now.''

Although I have tried many times since, I never found out what happened to Spoonbill. Wherever he is and whatever he's doing, I know he has got the situation pretty well in hand. But just now and again I have this slightly uneasy feeling he might have traveled in a different direction.