Henry of Langenstein, also known as Henry of Hesse the Elder (; born Heinrich Heinbuche; c. 1325 – 11 February 1397), was a German scholastic philosopher, theologian and mathematician. Biography Henry was born at Hainbuch (Hembuche), near Langenstein, in the Landgraviate of Hesse. He studied at the University of Paris, where he finished his M.A. in 1363 and his M.Th. in 1376, and became professor of philosophy there this same year. In 1368, on the occasion of the appearance of a comet, which the astrologers of his times claimed to be a sure foreboding of certain future events, he wrote a treatise entitled Quaestio de cometa, in which he refutes the then prevalent astrological beliefs. At the instance of the university he wrote three other treatises on the same subject, completed in 1373. On his scientific work, A. C. Crombie writes Oresme extended the impetus theory to psychology. One of his followers, Henry, while doubting whether the proportions and intentions of the elements of a given substance were knowable in detail, seriously considered the possibility of the generation of a plant or animal from the corpse of another species, for example of a fox from a dead dog. (Augustine to Galileo, Vol. 2, 1922, p. 114) When the Western Schism broke out in 1378, Henry sided with Urban VI against Clement VII, and wrote various treatises in defence of the former. In 1379 he composed "Epistola pacis" (see Helmstädter Program, 1779 and 1780) in which, under the form of a disputation between an Urbanist and a Clementine, he advocates the suppression of the schism by way of a general council or a compromise. In his Epistola concilii pacis, composed in 1381, and based on a similar work, the Epistola Concordiae of Conrad of Gelnhausen, he urges still more strongly the necessity of a general council and severely criticises the many abuses that were permitted to go on within the Church. These two treatises of Henry, and the Epistola Concordiae of Conrad, formed the basis of a discourse delivered by Cardinal Pietro Philargi, the future Alexander V, at the first session of the Council of Pisa (26 March 1409; see Bliemetzrieder in Historisches Jahrbuch (Munich, 1904), XXV, 536-541). Henry's Epistola concilii pacis is printed in von der Hardt's Concilium Constantiense, II, 1, 3-60, with the exception of the first and the second chapter, which were afterwards published by the same author