The Este Herbarium, preserved in the Este Secret Archives of the Modena State Ar- chives, is one of the few surviving Renaissance herbaria to date. It is the most fascinating and mysterious. It is probably the sixth volume of a lost series. In the present article, we discuss the results of a joint work (still in progress) among the Universities of Ferrara, Modena and Reggio Emilia, and Bologna.
All the correspondence between simplists and botanists of that epoch (primarily Ulisse Aldrovandi from Bologna) was thoroughly analysed, to search the solution of the rebus: which author (or authors), which temporal location, which context of production for this herbarium?
The documents consulted allow to understand that living plants, seeds and illustra- tions were commonly exchanged, but herbarium sheets never. The consultations on ta- xonomic attributions were frequent. The term herbario/herbarj, that is recurring in the letters written by Alfonso Cattaneo to Ulisse Aldrovandi, is also mysterious (thing or person?)