Jean de Roquetaillade
Jean de Roquetaillade, also known as John of Rupescissa, (ca. 1310 – between 1366 and 1370) was a French Franciscan alchemist and eschatologist. Biography. After studying philosophy for five years at Toulouse, he entered the Franciscan monastery at Aurillac, where he continued his studies for five years longer. His experiments in distillation led to the discovery of what he termed "aqua vitæ", or usually "quinta essentia", and commended as a panacea for all disease. His work as an alchemist forms the subject-matter of "De consideratione quintæ essentiæ" (Basle, 1561) and "De extractione quintæ essentiæ"; likewise "Libellus de  conficiendo vero lapide philosophico ad sublevandam inopiam papæ et cleri in tempore tribulationis" (Strasburg, 1659). His prophecies and violent denunciation of ecclesiastical abuses brought him into disfavour with his superiors, resulting in his imprisonment in the local Franciscan convents. During a transfer from one convent to another, he was able to reach Avignon and present an appeal before Pope Clement VI in 1349. While there he wrote in 1349 his "Visiones seu revelationes", and in 1356 "Vade Mecum in tribulatione" and "Liber Ostensor". His other works include commentaries on the "Oraculum Cyrilli", the recently discovered "Sexdequiloquium" and many other lost  treatises and commentaries on various prophecies. He died between 1366 and 1370, probably at Avignon. (1) editio princeps in: Edward Brown, "Fasciculus rerum expetendarum ac fugiendarum" II, London, 1690, Works. (2) modern editions (the authors edit different versions as the authentic text of Rupescissa: Tealdi takes for it the version of the family α, according to Kaup the secondary "Versio plena expolita"; Kaup holds for authentic the "Versio plena", according to Tealdi the secondary version of the family δ; the only double review so far (cf. Julia E. Wannenmacher in Journal of Ecclesiastical History 70.1 (2019), 165-166) recommends Kaup  for textual work and, as an essential complement to his factual commentary, Tealdi): a) Giovanni di Rupescissa. "Vade mecum in tribulatione", critical edition by Elena Tealdi, historical introduction by Robert E. Lerner and Gian Luca Potestà, Milan: Vita e Pensiero. Dies Nova, 2015, b) John of Rupescissa's "Vade mecum in tribulacione". A Late Medieval Eschatological Manual for the Forthcoming Thirteen Years of Horror and Hardship. Edited by Matthias Kaup, London/New York: Routledge. Church, Faith and Culture in the Medieval West, 2016.