It's not right for one to go through life not having been even once to a big three-ring circus with all the trimmings. So I made up for my childhood deprivation by a trip to the Ringling Bros. and Barnum & Bailey extravaganza - the real thing - at the D.C. Armory a couple of weeks ago. I had a grand time, though the whole spectacle was on the one hand a bit seedier and tackier, and on the other, less flamboyant than my envisionings (based on books, pictures, movies and TV).

In a way I suppose I came to it too late. The circus isn't quite what it used to be, and I'm not either. There's enough of the child left in me to be taken in by the wonders, but I'm too much an adult not to see how flaky and routinized it all looks around the edges.

In another way, though, I got more than I bargained for. Whether the circus is the "greatest" show on earth may be a moot point, but it's assuredly one of the strangest diversions ever devised. The experience sent me into dizzying ruminations about fear, fantasy and the nature of laughter.

As a kid, I had been taken to a small, intineran one-ring circus in the neighborhood, and my main memory from that was terror. The clown sticking his leering face in mine scared me, the animals frightened me, the side-shows repelled me and the whole bizarre business gave me nightmares. All this may say more about my neuroses than the circus. Nevertheless, there seems to be something inherently grotesque about circuses, something outlandish and even surreal, which is one reason artists have so often been turned on by them.

Outside the circus I went to as a child, in the surrounding amusement park, there was a mechanical laughing man - a mannikin behind glass, who rocked back and forth and chortled incessantly, in great gusty paroxysms. It made you laugh by contagion, but there was an edge of almost maniacal hysteria in its uncontrolability. The humor of the clown is like that, stadding the thin line between amusement and pain, wit and madness.

Why do we laugh at clowns? Why do we laugh at anything - say, the proverbial burlesque comedian who drops his trousers? It seems to me the heart of the joke here - and the essence of all comedy - is the revelation of man's animal nature, and thus, the unmasking of his pretensions to the divine. What the pants conceal is precisely the evidence of those needs and desires we have in common with the rest of the animal kingdom.

We smile or laugh in recognition of the link. We're been shown up for what we are - not gods, but upright beasts. Tragedy works the same way, but in the opposite direction. By their nobility or idealism or aspirations, our tragic heroes - from Odeipus and Hamlet to Willie Loman or Blanche DuBois - demonstrate man's proximity to godhood. Neverthless, it is the gulf that is emphasized.

Being human, the heroes are flawed. They sin, they err, they fall. We are moved to sympathetic tears because we recognize in them our own unconsummated strivings for perfection.

Tradedy shows us how close we can come to being gods. Comedy shows us how far we have yet to go. The proof, in the case of comedy, is by way of reminding us of our mortal biology - our appetites and our physicality. The clown's makeup suggests an almost simian creature, and he bounces around like a chimpanzee. In the circus, men behave like animals, and the animals are made to behave like men - to stand on two legs, to balance balls, to climb up ladders, to answer questions. There are also human feats ofdaring and strength - performers who fly like birds, lift great weights, eat fire or swallow swords. But again the point is human flesh-and-bloodedness.

Hamlet is not a great tragic figure because of his swordsmanship, but because his spirit is more finely tuned, more exquisitely troubled than those of most mortals. The straongman or the fire-eater, Does God have muscles? The question is its own answer.

In still another sense, the circus is an imaginative playground for the testing of human powers and qualities. Associated with circuses there have always been exceptional or freakish or abnormal beings - two-headed creatures, bearded ladies, dwarfs, giants. The sight of them taps into our dreams and fantasies about escaping human dimensions, trying on alternate attributes, seeing just how far one can go and still be a man or woman.

In her book "Styles of Radical Will," Susan Sontag discusses pornography as an art of exremes. The circus is an art of a similar kind. Like camp, or disaster movies, the circus is one of the means we have - a particularly ancient and enduring one - for exploring the limits of the human condition. The messages it delivers may be largely subliminal, but the "language" of the circus is basic and universal enough to be grasped by all ages and cultures. No wonder we all keep going back, mentally and otherwise.