The giant Picasso show that opened here last Thursday -- made up of artworks accepted by the French state in lieu of inheritance taxes -- is proof that the artist's deliberate public pose of nonchalance masked a creative intensity, a commitment to research and a continuity that even some of the leading Picasso scholars never really suspected.

"The net effect on this collection on the critics and scholars who have seen it so far," said Dominique Bozo, the show's organizer, "is that we are going to have to go back to square one in our judgements of Picasso's work.

"He didn't just throw things together with great ease. Everything was the result of hard work. There were no sudden breaks. Everything flowed from everything else."

At the opening, most of the Paris art critics wandering from room to room seemed to agree with Bozo, the man designated as the curator for the future Picasso museum which will house everything from the current exhibition in the Grand Palais, the 1900 World's Fair hall with huge carved Victorian skylights.

Standing before Picasso's 1906 "rose period" self-portrait, critic Pierre Schneider of l'express said, "this show will change the conception of how Picasso worked. He was thought of as capricious. His famous quote --' I don't seek, I find' -- is simply not true. We see here that the masterpieces seemed spontaneous. but that spontaneity was laboriously arrived at."

"Until now, Picasso was for us a language with vowels, but not consonants. Only by seeing the sculpture like this together with the pictures do we see that the sculpture provides the missing consonants."

One of the few well-known sculptures in the collection -- a seven-foot-tall shepherd holding a lamb -- is known to have been made in a day. But that prodigious effort is put in perspective when it becomes clear that Picasso made 80 sketches and studies on the same theme during the preceeding year.

Many of the works shown here were known to a tiny circle of specialists who had access to Picasso's studios, and many pieces had been photographed (often in black-and-white) in the complete catalogue of his works. But this show provides a sense of their real impact, size, texture and colors. b

Along with the 225 paintings, 159 sculptures and much more gathered in the Grand Palais, the mass of sketches and painted studies also show that -- far more than is generally realized --Picasso's work was the result of his "dialogues," both with great contemporaries like Braque and Matisse and with his predecessors.

The cubist abstractionism of "The guitar Player" and "The Mandolin Player" of 1911 are followed 10 years later by a roomful of monumental paintings and drawings in the soft, romantic style of Renoir. The six-foot tall canvas "The Reading of the Letter" -- painted by Picasso in 1921, two years after Renoir's death, and showing two young men hunched in contemplative study of a sheet of paper -- is only one of several works whose existence was not even suspected. Many others had been seen briefly, catalogued and largely forgotten. Still others like "Pan's Flute" (1923) were among Picasso's most important known works.

In a pyrotechnical display of technique and of the capacity to work almost any style, one of the most astonishing paintings in the show is a paraphrase of the 17th-century painter of French peasant scenes, Le Nair, done in the style of Seurat, the 19-th century impressionist who broke light and color into tiny dots.

Picasso explored almost every avenue opened by those around him. In September of 1911, Braque made the first collage. By October, Picasso was imitating him, and by spring of the next year he had produced the oval-shaped "Still-Life With Caned Chair" -- considered by many authorities to be the most sucessful of all, and a work that New york's Museum of Modern Art had unsucessfully tried to obtain from the artist.

The Grand Palais show also includes potteries, wood constructions, collages, sketches and engravings. An entire floor of the three stories devoted to the exhibit is given over to engravings.

"Picasso must now be accepted as one of the greatest engravers of all time," said an assistant to Bozo as she steered her way through the packing crates and pictures set on the floors along the walls before the show was hung. In passing, she deftly switched the labels on a pair of cubist wood constructions that the workmen had gotten wrong.

The French state collection is the result of three years of inventory, cataloguing and negotiations with Picasso's six heirs.

Under a 10-year-old law, the state can choose to accept major works of art instead of inheritance taxes. The total value of Picasso's works, scattered by the artist in bank vaults and in his residence across France, was officially estimated at $400 million, of which the state had a right to $75 million.

Once the courts had ruled that Picasso's three illegitimate children -- Maya, Claude and Paloma -- had equal rights, the heirs made no difficulties in letting the state take the first choice of what it wanted.

"Nothing important escaped us," said Bozo. "We even went back and added some items when we realized how cooperative the family was willing to be. They are getting a lot of important works. But we have at least one representative example of everything we wanted."

Aicardi said that "the removal of a large portion of Picasso's huge holdings from the art market was a stablilizing factor against the sudden break in values that would have followed if they had had to sell off things in a hurry just to pay the taxes."

In 1947, there was only one Picasso in a French museum. In 1966, Picasso went back on his plan to give France the wherewithal for a museum after a bitter personal dispute with culture minister Andre Malraux.

"The whole thing is miraculous," said Aicardi. "It is a miracle that Picasso kept everything. It is a miracle that the law was there so that we could acquire it. We never imagined the coherence, the quality, the completeness of Picasso's own collection."

The last Picasso exhibit, in Avignon -- heavily criticized at the time as rehash of old themes -- now, stands out for what it really was: a conscious summation that recalled works ranging from his arrival in Paris in 1901 to the last bold engravings.

At the opening of the new show -- which remains here through January before a number of the words go on loan to exhibitions in Minneapolis and New York -- French president Valery Giscard D'Estaing called Picasso the "chronicler of this century's sensibility."

Andre Malraux has described Picasso's work as "the greatest enterprise of destruction and creation of forms of out times and perhaps of all time." But this show proves that the master has a last surprise: There was far more creating than destroying.