From Classic Encyclopedia 1911
GEBER. The name Geber has long been used to designate the author of a number of Latin treatises on alchemy, entitled Summa perfectionis magisterii, De investigatione perfectionis, De inventione veritatis, Liber fornacum, Testamentum Geberi Regis Indiae and Alchemia Geberi, and these writings were generally regarded as translations from the Arabic originals of Abu Abdallah Jaber ben Hayyam (Haiyan) ben Abdallah al-Kufi, who is supposed to have lived in the 8th or 9th century of the Christian era. About him, however, there is considerable uncertainty. According to the Kitab-al-Fihrist (loth century), which gives his name as above, the authorities disagree, some asserting him to have been a writer on philosophy and rhetoric, and others claiming for him the first place among the adepts of his time in the art of making gold and silver. The writer of the Kitab-al-Fihrist says he had been assured that Jaber only wrote one book and even that he never existed at all, but these statements he scouts as ridiculous, and expressing the conviction that Jaber really did exist, and that his works were numerous and important, goes on to quote the titles of some 500 treatises attributed to him. He is said to have resided most frequently at Kufa, where he prepared the "elixir," but, according to others, he never spent long in one place, having reason to keep his whereabouts unknown. His patron or master is variously given as Ja'far ben Yahya, and as Ja'far es-Sadiq; in the Arabic Book of Royalty, professedly written by him, he addresses the last-named as his master. In addition to these details the Fihrist mentions a tradition that he originally came from Khorasan. Another story given by d'Herbelot (Bibliotheque orientale, s.v. " Giaber") makes him a native of Harran in Mesopotamia and a Sabaean. Leo Africanus, who in 1526 gave an account of the Alchemists of Fez in Africa (see the English translation of his Africae descriptio by John Pory, A Geographical History of Africa, London, 1600, p. 155), states that their principal authority was Geber, a Greek who had apostatized to Mahommedanism and lived a century after Mahomet. In Albertus Magnus the name Geber occurs only once and then with the epithet "of Seville"; doubtless the reference is to the Arabian Jabir ben Aflah, who lived in that city in the r r th century, and wrote an astronomy in 9 books which is of importance in the history of trigonometry.
The great puzzle connected with the name Geber lies in the character of the writings attributed to him, their style and matter differentiating them strongly from those of even the best authors of the later alchemical period, and making it difficult to account for their existence at all. The researches of M. P. E. Berthelot threw a great deal of light on this question. Taking the six treatises enumerated above he concluded, after critical examination, that the two last may be disregarded as of later date than the others, and that the De investigatione perfectionis, the De inventione and the Liber fornacum are merely extracts from or summaries of the Summa perfectionis with later additions. The Summa he therefore regarded as representative of the work of the Latin Geber, and study of it convinced him that it contains no indication of an Arabic origin, either in its method, which is conspicuous for clearness of reasoning and logical co-ordination of material, or in its facts, or in the words and persons quoted. Without going so far as to deny that some words and phrases may be taken from the writings of the Arabian Jaber, he was disposed to hold that it is the original work of some unknown Latin author, who wrote it in the second half of the r3th century and put it under the patronage of the venerated name of Geber. The MS. of this work in the Bibliotheque Nationale at Paris dates from about the year 1300. Berthelot further investigated Arabic MSS. existing in the Paris library and in the university of Leiden, and containing works attributed to Jaber, and had translations made of six treatises - two, of which he gives the titles as Livre de la royaute and Petit Livre de la misericorde,-from Paris, and four - Livre des balances, Livre de la misericorde, Livre de la concentration and Livre de la mercure orientale - from Leiden. Berthelot was not prepared to assert that these treatises were actually written by Jaber, but he held it certain that they are works written in Arabic between the 9th and 12th centuries, at a period anterior to the relations of the Latins with the Arabs. In style these treatises are entirely different from the Summa of Geber. Their language is vague and allegorical, full of allusions and pious Mussulman invocations; the author continually announces that he is about to speak without mystery or reserve, but all the same never gives any precise details of the secrets he professes to reveal. He holds the doctrine that everything endowed with an apparent quality possesses an opposite occult quality in much the same terms as it is found in Latin writers of the middle ages, but he makes no allusion to the theory of the generation of the metals by sulphur and mercury, a theory generally attributed to Geber, who also added arsenic to the list. Again he fully accepts the influence of the stars on the production of the metals, whereas the Latin Geber disputes it, and in general the chemical knowledge of the two is on a different plane. Here again the inference is that the Latin treatises printed from the 15th century onwards as the work of Geber are not authentic, regarded as translations of the Arabic author Jaber, always supposing that the Arabic MSS. transcribed and translated for Berthelot are really, as they profess to be, the work of Jaber, and as representative of his opinions and attainments.
XI. 18 But while Berthelot thus deprived the world of what were long regarded as genuine Latin versions of Jaber's works, he also gave it something in their place, for among the Paris MSS. he found a mutilated treatise, hitherto unpublished, entitled Liber de Septuaginta (Tohannis), translates a Magistro Renaldo Cremonensi, which he considered the only known Latin work that can be regarded as a translation from the Arabic Jaber. The latter states in the Arabic works referred to above that under that title he collected 70 of the 500 little treatises or tracts of which he was the author, and the titles of those tracts enumerated in the Kitab-al-Fihrist as forming the chapters of the Liber de Septuaginta correspond in general with those of the Latin work, which further is written in a style similar to that of the Arabic Jaber and contains the same doctrines. Hence Berthelot felt justified in assigning it to Jaber, although no Arabic original is known.
The evidence collected by Berthelot has an important bearing on the history of chemistry. Most of the chemical knowledge attributed to the Arabs has been attributed to them on the strength of the reputed Latin writings of Geber. If, therefore, these are original works rather than translations, and contain facts and doctrines which are not to be found in the Arabian Jaber, it follows that, on the one hand,the chemical knowledge of the Arabs has been overestimated and, on the other, that more progress was made in the middle ages than has generally been supposed.
See M. P. E. Berthelot's works on the history of alchemy and especially his Chimie au moyen age (3 vols., Paris, 1893), the third volume of which contains a French translation of Jaber's works together with the Arabic text.