The sculptor Joan Grau was one of the most talented artists in the Manresa School of sculpture during the Baroque period. His works and those of his son Francesc can be found all over Catalonia (Tarragona, Cardona, Poblet, Lleida, Barcelona, etc.).
In around 1642, he executed the Roser altarpiece for Sant Pere Màrtir church in Manresa. Due to its formal characteristics, it became a model for this kind of altarpiece. The Nativity panel is the richest piece in the entire work; it was sculpted by Joan Grau and polychromed by Gabriel Adrià and Magí Torrabruna.