In Cinquecento art, the fundamental principle of any artistic activity was drawing (disegno). For Giorgio Vasari disegno involved practical and theoretical considerations. During the span of his artistic career, the Aretine artist found himself more than in one occasion in the role of a “modern designer” – an inventor of figurative repertoires and of entire compositions, which originally were created by others artists or patrons.

This type of artistic activity as a “modern designer” was not limited to the creations of drawings, or inventions from his collaborates, e.g., the imprese in the decoration of Palazzo Vecchio, but also included the labour of supervising artistic initiatives of other artists, who were not active in his bottega. A clear example is the case of the Bolognese Prospero Fontana, who during his artistic career engaged in a privileged relation with Vasari. From their collaboration, Prospero assimilated complex artistic notions as well as artistic repertoires in the formation of his work. This essay traces aspects of their collaboration, paralleling them with readings in Vasari’s Lives. The goal is to reveal Vasari’s thoughts on the process of exchanging drawings among artists as in the example of Michelangelo and Sebastiano del Piombo.