Why are dealer stock books so valuable for provenance research? In their stock books, dealers recorded crucial information about the artworks they purchased and sold. For example, in addition to the title, creator and dimensions of the artwork, sometimes they kept track of past owners, changes in the artistic attribution, and monetary values. Furthermore, they typically indicated the date of acquisition, the name and address of the seller, as well as the name of the purchaser, date of sale, and the selling price. All this information is key for reconstructing the trajectories of objects, as they changed hands and travelled across time and geographies.