New York, summer, 1923. Into the office of writer-critic Carl Van Vechten walks this Mexican kid, this 18-year-old curly-haired cherub with a couple of introductions and a portfolio of drawings of Mexican officials.

"I was immediately convinced that I stood in the presence," Van Vechten later wrote, "of an amazing talent, if not, indeed, genius."

Van Vechten, very big in the self-dazzled extravaganza that was New York then, took the boy to the Algonquin Hotel, where all the clever people met. The lunch turned into a reception, which turned into a triumph. By midafternoon Miguel Covarrubias was famous.

In this era so lacking in brilliance or wit, it is no wonder that his work jumps right off the wall. The National Portrait Gallery's generous show on the great caricaturist lasts through Jan. 13; there is absolutely no excuse for not seeing it.

Look at these pictures carefully. They are not just glib sketches. They are masterly character studies. Yet more. They are Art.

Today, shown the grinning photographs of bygone celebrities, we see merely their disappointingly ordinary faces, and we wonder why they were so exciting. Covarrubias captured the vitality, the unique quality, the something in these people that made them icons in their time.

Study Paul Whiteman, the rotund bandleader who dressed jazz up in white tie and tails. The head is a sheer circle, enclosing an arc for the double chin and a few geometric shapes that make the slit eyes, the tiny nose, the pencil mustache. The face is frontal and profiled at the same time, a la Picasso, and the chest becomes a violin, a la Braque.

Look at Alfred Stieglitz. A gnome face with its magnified, intensely seeing artist's eyes, peers out from behind coat collars that jut up like the skyscrapers he photographed. We fix the man immediately: shy, passionately observant -- and short. Now, how do we know he was short?

Conductor Walter Damrosch -- straight lines and a few Art Deco curves. We would recognize him anywhere. We could never forget that face. There is more Damrosch in it than any photo could contain.

Igor Stravinsky. He looks exactly like a grasshopper. Why hadn't we seen that before?

The economy of line is breathtaking. The black skin of poet James Weldon Johnson is suggested simply by a small strip of crosshatching over the eyes. The long fingers of Noe l Coward are like animated cigarettes -- expensive English cigarettes at that. The India-ink orbs of Eugene O'Neill's eyes convey fear, a hidden, permanent fear that one had never noticed. The laconic ink-wash profile of publisher Joseph Medill Patterson consists of a single line for the entire head, one line each for the chin, nose and mouth, four marks for crow's-feet. There are no eyes at all, just brows. Yet there he is, brooding, ruthless, secretive.

How can a few marks on paper give us such insight into character?

Some pictures, especially the later ones, are not quite as successful. The Franklin Roosevelt of 1934 has the genial, professional grin but not the ebullience. The William Faulkner, as a bad boy in shorts, misses the writer's remote, contained quality. Perhaps Covarrubias outgrew caricature. He returned to Mexico in the '40s to write and teach, and died much too young, at 52, in 1957.

But the works are a joy at any time. The lines, whether Cubist or Mayan geometric motifs, whether parodies of Modigliani and Chirico or hieratic pre-Columbian designs, as gallery director Alan Fern observes, still delight. Eyes may be marbles, slits, stars or polliwogs (as in Fred Allen). Fingers may be Disneyesque paws, filed-off stubs (as in Herbert Hoover) or elegantly expressive hooks (as in the deadly pinky-curling, tea-sipping portrait of Emily Post reading the Police Gazette with her feet up on the desk).

Covarrubias' colors, overstated yet subtle, often startling, are famous, but it is the line that carries his wicked message. As caricaturist Al Hirschfeld, who once roomed with him, suggests, the piercing light of Mexico washes out shadings and forces its artists to rely on pure line.

Yet there is more here than technique. Covarrubias still seems fresh because he is never mean or spiteful, because his boyish humor mocks not the waspish critic or the truculent author or the vain politician, but the human condition itself. The playful "Impossible Interviews" pair off hilariously unlikely couples: John D. Rockefeller Sr. and Joseph Stalin, Haile Selassie and Joe Louis, Noe l Coward and Will Rogers, Sally Rand and Martha Graham, and so on, complete with dialogue.

Clare Boothe Luce, who appears as a horn-tooting angel in the FDR Inaugural fantasy, wrote some of these dialogues. (Sigmund Freud: "My dear Miss Harlow, I've been looking for you for years. I want to analyze you." Jean Harlow: "You cad! You men are all alike . . .")

One reviewer noted that Covarrubias appeared in New York just when "we were on the point of exploding with our own importance. He began at once to giggle at us . . . To be seen through so easily by a boy of 20, and by a Mexican, a national of a country that we have been patronizing for a century or two . . . it was a bitter but corrective pill."

Oh, you, Miguel. Where are you now that we really need you?