The primary source for musical and theatrical activities during the reign of Ferdinand VI and Barbara of Portugal is the 1758 manuscript titled Descripción del estado actual del Real Theatro del Buen Retiro: de las funciones hechas en él desde el año de 1747 hasta el presente, commissioned by Farinelli. Three copies are believed to have been produced, with one located in the Royal Palace of Madrid and another in the library of the Collegio di Spagna in Bologna. The first part meticulously documents the operas performed at the Royal Theater of Buen Retiro, providing insights into singers, orchestras, choirs, extras, librettists, tailors, set designs, lighting practices, and various other aspects related to production. The narrative is complemented by several illustrations, including a scene from an opera performance, and shows the stages of preparation and construction of the sets.