From the Bonhams website:
Mario Gregorio is a recognised authority on Nostradamus, the author of four books on the subject, and former Archivist of the International Nostradamus Research Group.
Mario developed an interest in the prophecies of Nostradamus at an early age. After arriving from his native Veneto in the 1990s, he began to get heavily involved in collecting, researching and comparing the many variant editions, piracies and spurious works. The result is the website of this self-styled “crazy collector of old books about renaissance prophecies”, an extraordinary resource with thousands of uploaded images not only of the books in his own collection, but also those of many others.
Many of the books in the present sale were bought in 2007 at the New York sales of Daniel Ruzo de los Heros (1900-1991), noted Peruvian archaeologist, poet, cryptographer and prophet. Ruzo was perhaps the last of the great Nostradamus collectors, as Mario Gregorio would modestly admit, but he now feels the time is right to give younger collectors, researchers and institutions the opportunity to continue his work.