From experiment to alchemy is an easy step, for the alchemists experimented a good deal in the period which we are now considering. The fourth book of the _Meteorology_ of Aristotle, which, if not a genuine portion of that work, at least goes back to the third century before Christ,[763] has been called a manual of chemistry,[764] and apparently is the oldest such extant. Its doctrines are also believed to have been influential in the development of alchemy; and there were passages in this fourth book which led men later to regard Aristotle as favorable to the doctrine of the transmutation of metals. Gerard of Cremona had translated only the first three books of the _Meteorology_; the fourth was supplied from a translation from the Greek made by Henricus Aristippus who died in 1162; to this fourth book were added three chapters translated by Alfred of England or of Sareshel from the Arabic,[765] apparently of Avicenna.[766] These additions of Alfred from Avicenna discussed the formation of metals but attacked the alchemists.[767] Vincent of Beauvais[768] and Albertus Magnus[769] were both aware, however, that this attack upon the alchemists was probably not by Aristotle. The short treatise _On colors_,[770] which is included in so many medieval manuscript collections of the works of Aristotle in Latin,[771] by its very title would suggest to medieval readers that he had been interested in the art of alchemy, although its actual contents deal only in small part with dyes and tinctures. Its form and contents are not regarded as Aristotle’s, but it was perhaps by someone of the Peripatetic school. Thus works which, if not by Aristotle himself, at least had been written in Greek long before the medieval period, gave medieval readers the impression that Aristotle was favorable to alchemy. [Sidenote: Works of alchemy ascribed to Aristotle.]