History of Science and Technology in Islam
The Arabic Origin of Summa perfectionis magisterii
And the Other Geber Latin Works
“Our Volumes” of Geber
An Evident Proof to the Arabic Origin of the Latin Works
In every one of the four Latin tracts Geber speaks of his other “volumes”. We provide below twelve citations in which Geber refers to his other “volumes” or “books”.
Geber says that the Summa is the sum of what he had written in his other “volumes.” Obviously those other “volumes” or “books” cannot be the three small tracts that are associated traditionally with the Summa. There are several reasons for this:
1. The Summa is a larger work, and a large book cannot be the sum of three much smaller discourses. To give an idea of the comparative sizes of the four tracts, here is the approximate number of words in Russell’s translation:
Summa: 48194 words
De investigatione 4028 words
De inventione 6092 words
Liber fornacum 5823 words
2. Most of the theories and basic principles of the Art of alchemy that are expounded in the Summa do not occur in the three other short tracts. Therefore the Summa as a sum of Geber’s other “volumes” should be referring to a larger number of earlier books that have been written by him.
3. The Summa does not contain the same information that is given in the other three short tracts. The latter are practical treatises describing processes and giving formulae and recipes of chemical preparations. They mention materials that are not pointed out in the Summa. In other words the Summa is not a sum of the other three tracts. Hence “our volumes” to which the Summa refers are definitely other earlier works of Geber.
4. Even if we allow for the improbable possibility that “our volumes” refer to the three shorter tracts, it follows that the Summa should be of a later date than these. However, “the De investigatione, De inventione and Liber fornacum all cite the Summa, and in ways which make it seem a prior work” Therefore “our volumes” as mentioned in the Summa refer to different earlier works and not to the three smaller tracts.
5. We have pointed out in one of our Brief Notes  that the name of the translator of the Liber fornacum is mentioned in some Latin versions of this treatise. Thus the Liber fornacum should be removed from the list of the works of a Pseudo Latin author leaving, for now, only De investigatione and De inventione, which give further proof that these two tracts cannot be the “volumes” to which Geber refers.
6. Although we dispute the assumptions of the advocates of a Latin Pseudo- Geber since they are based on speculation or feeble evidence, yet we must mention that Berthelot reached a conclusion that the three short tracts were written after the Summa because they contain more advanced information. For different reasoning Newman thinks that each of the three tracts was written by a different author who is not the same as the author of the Summa. Both of these assumptions confirm that “our volumes” in the Summa cannot refer to the short tracts.
All this leads us to believe that the phrase “our volumes” that is repeated in every one of the four Latin works indicate an author who did actually write numerous works on alchemy. Such an author cannot obviously be the Pseudo-Geber. The only writer who composed scores of treatises and books on alchemy and who repeatedly refers to his other books or volumes in most of his works is Jabir ibn Hayyan. It is his unmistakable style.
We do not give an assumption here, we are rather trying to draw the attention of historians of science to basic and simple facts that are so close to our eyes but of which we are oblivious.
We can give many Arabic citations from Jabir’s Arabic works in which he refers to his “our books” كتبنا . It suffices to give one item only. This is taken from Kitab al-manfa`a  كتاب المنفعة or the Book of Benefit.
Jabir says here:
“Understand that we have compiled in this art many books in numerous topics and arranged them in several ways. Some were interrelated to others and some were comprehensive. It is obvious for men of intelligence that the comprehensive are more valuable than those that are related to others. Each book that is comprehensive is made in this manner so that it will be adequate on its own.
As to those books that are interrelated, each one needs the other, and no person can work by using them unless he gets hold of a complete collection (and) read them all and learn their purposes.”
We shall give now twelve citations from the Latin works in which Geber refers to “our volumes” or “books”:
De investigatione p.18 :
Therefore from the above premised, the Things are manifest in which the Verity of the Work is nigh; and we have considered Things perfecting this Work, by our true Investigation, with certain Experience, whereby we of are assured, That all the Words are true, which are now (by us only) written in our Volumes, according as we found by Experiment and Reason, related in the same: But those Things which by our Experience we have operated, seen with our Eyes, and handled with our Hands, we have writ in the Sum of the Perfection of Our Magistery. Therefore, let the Sapient Artificer studiously peruse Our Books, collecting Our dispersed Intention, which we have described in diverse places, that we might not expose it to Malignant and Ignorant Men; and let him prove his Collection even unto Knowledge, Studying and Experimenting with the Instance of Ingenious Lahour, till he come to an intire Understanding of the whole.
De investigatione p. 19
By which Consideration we came to the perfect and compleat end to of this Science, which we have perfectly described in Our Books. Therefore be Studious in them, and you will find Our whole Science out, which we have abbreviated out of the Books of the Ancients.
Our whole Science of Cbymistry, which, with a divers Compilation, out of the Books of the Ancients, We have abbreviated in our Volumes; we here reduce into one Sum.
Summa p. 24
Wherefore labour studiously in Our Volumes, and endeavour to ponder them very often in your Mind, that you may acquire the true Intention of Our Words; because in them you may find whereon to establish your own Mind, and by them know how to escape Errors, and in what you may be able to imitate Nature in the Artifice of your Work.
De inventione p. 201
We have in our Volumes considered, not only by the Secret Properties of Natural Principles, but also by proper Experience, and the truly certain Investigation -of our Invention, that those Things, from which our Medicine is extracted, have in themselves these Properties of Qualities, in transmuting Bodies.
De inventione p. 214
We will set down all Waters dissolutive of Spirits and Bodies, in the End of this Book; and every One of these according to its own kind: and wonder not, that We have dispersed the special Things pertinent to this Praxis, in diverse Volumes, seeing We endeavour to hide the Art from evil Men.
De inventione p.221
But do you direct your Hands according to our Sayings, otherwise you Study in vain; and in your Heart receive our Intention (expressed in our Volumes) for so doing you will discern, that we have made a true search. 
Liber fornacum p. 227
WE have considered with a Consideration not phantastick. That in our Volumes We have amply treated of the whole Art.
Liber fornacum p. 229
Calcination is the Treasure of a Thing; be not you weary of Calcination; but study what We have said in Our Volumes.
Liber fornacum p. 240
By this Furnace, and by this Way the Ancient Philosophers attained to the Work of the Magistery; which, Men truly Philosophizing, is known to be sufficiently demonstrated in Our Books; and by those especially, who are true Searchers of V erity.
Liber fornacum p.253
For if you well Study in Our Volumes, you will find by Our Consideration, upon what Subjects, the true Searcher ought to ground his Action.
Liber fornacum p. 254
Therefore keep this Book, even from thy own Son; because it expounds all Things, which We have Written in divers Books.
We summarize as follows:
1. Every one of the four Latin works of Geber refers the reader to Geber’s earlier “volumes” or “books, The phrase “our volumes” is repeated. We have given above twelve such citations.
2. The Summa cannot be the sum of the three short treatises of the De investigatione, De inventione or the Liber fornacum.
3. As given in the Latin texts of Geber the phrase “Our volumes” imply a reference to many earlier books written by Geber.
4. Of all authors on alchemy until the end of the thirteenth century both in the Arabic and the Latin worlds the only author with such voluminous writings was the Arab Geber or Jabir ibn Hayyan, who usually refers the reader to his earlier books in most of his works.
5. It follows that Geber of the four Latin works is none but Jabir ibn Hayyan.
 Robert Multhauf raised the question as to what “our books” in the Summa may refer.
on page 171 of The Origins of Chemistry , London, 1966.
 Multhauf, p. 174
 See The Origin of Liber Fornacum in the Brief Notes on this web site.
 Berthelot, M. La Chimie au Moyen Age, Tome I, Paris, 1893, p. 343
 Newman, W., The Summa Perfectionis of Pseudo-Geber, Brill, 1991, pp. 81-82
 كتاب تدبير الاكسير الاعظم – اربعة عشرة رسالة في الكيمياء لجابر بن حيان – حققها بيير لوري – دمشق- 1988
L’élaboration de l’élixir suprème , Jabir ibn Hayyan, ed. Pierre Lory, Damas, 1988
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