When Frits Lugt purchased two of the surviving seven letters written by Rembrandt, he was laying the foundations for what would become one of the most extensive parts of the Fondation Custodia’s collection. It was primarily his successor, Carlos van Hasselt, the director from 1970 to 1994, who boosted the expansion of the modest group put together by Lugt, which centred on unique letters by great artists of the sixteenth and seventeenth centuries, into an encompassing archive with artist’s documents from all countries and all times. An active acquisition policy has seen the number of items grow to more than fifty thousand, spanning a period from the late fifteenth century to the present day. Apart from countless individual items, the collection contains a number of comprehensive correspondences and archives, and it includes writings by or documents concerning collectors, art critics and art historians. It is still being expanded and increases by some hundreds of items each year.

The Rembrandt letters, one of the letters Albrecht Dürer wrote to his friend Willibald Pirckheimer during his stay in Venice in 1506, a letter from the eighty-seven-year-old Michelangelo to Cosimo I de’ Medici and a letter from Titian to Emperor Charles V, together with illustrated letters by Édouard Manet and Paul Gauguin, are just some of the highlights.

The lion’s share of the collection is made up of letters from French artists of the eighteenth and nineteenth centuries. The great masters of this period, from David to Monet and Degas – are all represented with several specimens of their handwriting, and not infrequently – as in the case of Ingres – with sizeable dossiers. But the collection also comprises countless writs by lesser known or obscure artists, many of them unpublished, that make it a treasure trove for the art historian. Among the larger files are those from (or relating to) Jean-Pierre Hoüel, Aignan-Thomas Desfriches, Antoine Étex, Théophile Thoré-Bürger, Victor Geoffroy-Dechaume, Henri Fantin-Latour, Léon Lhermitte, Émile Bernard and the Goncourt brothers. The collection houses substantial parts of the archives of Paul Baudry and Alfred Philippe Roll.

But the collection also boasts numerous letters by Dutch, Belgian, German, Swiss, English, Italian, Spanish, Scandinavian and American artists. Important files concern the Schnorr von Carolsfeld family and Max Liebermann, while a bequest from the artist Dimitri Bouchène (1893-1993) brought important material by Russian artists such as Ilja Repin, Mark Antokolski and Alexandre Benois to the collection. With the correspondence from Piet Mondrian and Theo van Doesburg to the architect J.J.P. Oud, both running to a hundred of letters, the Fondation also holds material of great significance from the twentieth century.