This column first appeared June 18, 2012.

An act of God sometimes forces price gyrations in the art market.

When an artist dies, the number of paintings he will create in his lifetime suddenly reaches its finite end. (Except for forgeries.) That can make prices go up. It's the law of supply and demand.

As the artist's work disappears into public collections, the number that might come on the market shrinks. That's one of the reasons French Impressionist paintings bring skyrocketing prices. Collectors with money want them, but there aren't a whole lot of them available anymore.

This does not always happen. Unless the deceased has an ambitious dealer or followers who are determined to keep the artist's name and works in the public eye, the artist may become forgotten, and the market collapses, at least momentarily.

Death is not the only act of God that intervenes. Take Mario Prassinos (1916-1985).

Prassinos was born in Constantinople (now Istanbul). However, he and his younger sister Giselle grew up far from the bright Turkish sun in Nantere, France, where they were taken by a despotic Greek grandmother and French step-grandfather.

Both Mario and Giselle were prodigies. By 1938, when he was 22 and she 18, they were Paris celebrities, Mario as a painter, Giselle as a writer. Her writings were discovered by Surrealist painter André Breton (1896-1966) when she was just 14. Soon she was being printed in Surrealist publications. Sometimes Surrealist, Mario was equally successful as a painter, one of many comprising the School of Paris.

During World War II Giselle began writing a short novel l'Armurier de Bordeaux, for which her brother did illustrations. In 1946 the works remained unpublished in book form, but there were a couple of unbound trial copies, words and art, and one of these has been on the current market for $6632.

By the time I met Prassinos in 1958, he had become one of France's foremost tapestry creators. I did not yet know that he was one of the few tapestry cartonniers who had an equal reputation as a painter.

His great tapestry Winter was the hit of a tapestry collection, which I arranged with the Smithsonian Institution Traveling Exhibition Service, that attracted record crowds in 20 U.S. museums in 1959-61. His tapestry Oiseaux Jaunes de Printemps/Meadowlarks was the tapestry that began my own collection. Mine was the third weaving and, as it turned out, the last.

A tapestry artist creates his original design in tempera on heavy paper. This is called a cartoon. By French law, six individual weavings maximum are permitted for each cartoon.

The Prassinos cartoons were handwoven in the workshop of Suzanne Goubely in the quaint French village of Aubusson. Her atelier occupied an ancient two-story stable next to the Creuse river. Weaving was done on the upper floor, and wool and cartoons were stored below.

In the fall of 1961, Aubusson was hit with floods more severe than any seen in 200 years. Waters roiled through the second floor of Goubely's. The loss to Prassinos was catastrophic: 35 cartoons, a decade of work, destroyed. Most of the cartoons had been woven only once or twice. They could never be woven again.

Mario's catastrophe was a windfall for those owning completed weavings, which became worth significantly more than their original prices. Owners did not rush to sell.