Jean des Murs, Astrologer

Jean des Murs wrote two astrological predictions: a prognostication for the conjunction of the three superior planets—Saturn, Jupiter, and Mars—in 1345 and a letter to Pope Clement vi concerning the conjunctions of Saturn and Jupiter in 1365 and of Saturn and Mars in 1357. The prognostication was probably written when Jean des Murs was in Avignon, working with Firmin de Beauval on the calendar reform sponsored by Clement vi. The letter on the conjunctions of 1365 and 1357 was necessarily addressed to Clement vi before his death in 1352. In this article we try to ascertain the Alfonsine astronomical substratum of these astrological judgments in order to understand their reasoning, context, and motivations, but also to gauge their significance and impact from the mid-fourteenth century to the following.