Abstract

This paper wonders why the Franciscan order took part in the diffusion of optics more than other medieval organisation, both religious and secular. First, clues of this social asymmetry are given. Then, an explanation is put forward: 1. An initial asymmetry existed, by the fact that Grosseteste’s optics was known in the Franciscan studium of Oxford; 2. Since that date, optics spread among the order by a network effect; 3. The rivaltry between the mendicant orders and the homophilia that presided over their conventual libraries’ purchasing policy finally explains why other contemporary organizations, similarly structured, took a smaller interest into optics. In spite of an evident topical connection, this explanation deeply differs from the analysis that has been applied to the Puritans’ and Jesuits’ scientific activity in XVIIth and XVIIIth centuries classical Europe. It does not appeal to the heavy hypothesis of ethos in order to understand scientific development.