The following is a list of the rasa'il (epistles) which compose the influential Neoplatonic encyclopedia, the Encyclopedia of the Brethren of Purity composed by the Brethren of Purity in the tenth century CE in Basra, Iraq.
The following tabulation of the rasa'il is principally drawn from a work entitled "Notices of some copies of the Arabic work intitled "Rasàyil Ikhwàm al-cafâ"", written by Aloys Sprenger, originally published by the Journal of the Asiatic Society of Bengal (in Calcutta) in 1848. Doubts have been raised by A. L. Tibawi as to the accuracy of Sprenger's catalogue: "But it is unfortunate that his account is marred by loose translation and too many misreadings of or misprints in the Arabic, and his collection omits the fourteenth tract, merges the eighth with the ninth, and leaves the text of the twelfth and thirteenth confused."
Mathematical Sciences
Numbers, arithmetic, and numerology, especially Pythagorean; a discussion of the importance of the number four Geometry (jumatriya). Euclid's definitions and how to calculate the area of a triangle Ptolemaic astronomy (asturunumiya) Geography (al-jughrafiya), especially geography that uses mathematics. The Brethren explain racial characteristics as resulting from varying climates' long-term influence."However, differences exist between the races and nations of the earth. According to the theory of racial differences, which we also find in the same context in al-Kindi: the particularizing and characterizing signs that distinguish nations and races are not the results of inheritance, but are caused by the place the various groups inhabit, and its climate." page 8 of Shiloah 1978 The Brethren seem to know of Japan: "The most eastern country of this climate is the island of Niphon [compare another term for Japan, "Nippon"]; then comes southern China, then the south of Ceylon, then central India, then subcentral and Sindh, then beyond the Persian Gulf the south of Oman then comes the centre of the country of Shir, then central Yaman, then across the Red Sea, central Messynia ; then across the Nile is Nubia.....""Notices of some copies of the Arabic work entitled "Rasàyil Ikhwàm al-cafâ"", written by Aloys Sprenger, originally published by the Journal of the Asiatic Society of Bengal (in Calcutta) in 1848 Music (al-musiqa) deals with the subject in unusually many aspects."When I originally undertook to prepare this text for publication, it very soon became clear to me that this treatise in its range, construction, purpose and richness of thematic material was unique of its kind, both in the Arabic musical literature that preceded and followed it and, perhaps, in the whole of medieval musical literature." page 5 of Shiloah 1978. It first lays out the power of music and its uses; it uses the practical purposes of music "If one establishes the measure of time by the regular, harmonious and proportionate succession of motions and silences, the notes resulting will be comparable to the notes produced by the movements of the sphere and the heavenly bodies and in concordance with them. Thus doing, the individual soul that inhabits the world of generation and corruption, will recall the beatitude of the world of the spheres and the felicity of the souls who are there above. It will know and will acquire the conviction that the souls of the celestial world enjoy the best conditions, the sweetest delights and the most lasting felicity, for the notes produced by the movements of the spheres are purer, their melodies sweeter; for these celestial bodies are of a better constitution, of a more beautiful form, of a purer substance, their movements are better ordered and their concordance is more harmonious. When the individual soul that inhabits the world of generation and corruption will have acquired a knowledge of the states of the celestial world, will have had faith in the truth of what we have described, it will manifest an ardent desire to mount upwards and to join there the souls of its own kind, delivered from nations that disappeared in earlier times." page 35 of Shiloah, 1978. as a defense against various Koranic proscription; another defense is that the restrictions are applicable only to entertainment and pleasure motivated music, analogous to contemporary defenses of poetry). Theologically motivated, it moves on to the abstracted essence of music, which is present in all arts."This is the art of harmony (tayif) which can be defined in terms of proportions. Our intention in this Epistle is not therefore the teaching of the practice of music (ghinī); nor of the instrument art (sinālat al-malāhī), although the study of this aspect is indispensable, but our purpose is to make known the science of proportions and the modality of harmony, the knowledge of which presides at mastery in all the arts." page 12 of Shiloah 1978 Deals with ratios and proportions, which are useful in mathematics and also especially in musical scales; indeed, Thomas Davidson describes there assertion thus: "The faculty of aesthetic judgement investigates these properties, and so discovers the rules of Art." Eric van Reijn classifies this epistle as dealing with "Mathematics and Geometry".pg. ix of Reijn 1995 The seventh and eighth epistles are the "Classification of the Sciences", or "On the scientific arts": The nine professional sciences are "the educational sciences, intended to help men to a maintenance, and to direct them in their intercourse with others." They are: reading and writing; grammar and language; arithmetic; sorcery and alchemy and shorthand; "Versification and poetry" or "poetry and music";pg 198-199, Lane-Poole 1883 business and agriculture; "trades and professions"; selling, buying, and other things of commerce like breeding cattle; and finally, biographies and histories. The 6 religious sciences "help the soul in its struggle towards the other world."pg 199, Lane-Poole 1883 They consist of: learning the Koran (revelation); learning the Koran's commentaries (explanation); of the hadith and other traditions (tradition); "the knowledge of law and ordinances of God and of legal division" (law); religious obligations and asceticism; and oneiromancy ("illumination"). The given hierarchy of philosophical sciences is complex. It appears to be as follows: Mathematical sciences Arithmetic Geometry Astronomy Music Logic Poetry Rhetoric Topica Analytica Sophistica Natural philosophy "Sciences of the first principles of a body" Matter Shape Time Place Motion "Science of the heavens and of the universe" What the heavens are made of How many bodies there are in the heavens Why those bodies move Whether those bodies can be destroyed like mundane matter "de generatione et corruptione" The nature of the four elements The influence of stars on the sublunary world Meteorology Mineralogy Zoology Metaphysical sciences Theology Knowledge of angels Knowledge of dead souls Knowledge of governments "Science of things connected with a future state" "On creeds and professions"- a classification of the sciences into three categories of professional, religious, and philosophical sciences. The Brethren write: "Know, my brother, that there are three kinds of sciences with which people are busy, namely: the propaedeutic sciences, the religious and conventional sciences, the philosophical and real sciences." This chapter deals especially with the practical arts. 9. "Where one accounts for characters, the causes of their difference and the [various] species of the evils which [strike] them; anecdotes drawn from the educational rules of the Prophets and cream of the morals of the sages." (from Sprenger). "No. 9 examines the differences of Temperament and Character, with the view of enabling the soul to attain the proper mood and develop a perfect character. Here we have a system of Ethics." (from Thomas Davidson). 10. A summary of Porphyry's Isagoge (the Latin name for his Introduction to Categories, sometimes simply Introduction). 11. A summary of Aristotle's Categories, a portion of his Organon; it tries to encompass all things under the ten categories of Aristotle. 12. A summary of De Interpretatione, another subsection of his Organon; an essay defending the usefulness of logic in general is included after its discussion of Aristotle's propositions. 13. A summary of Prior Analytics, another work included in Aristotle's Organon 14. A summary of Posterior Analytics, another work included in Aristotle's Organon
Natural Sciences According to Sprenger and Godefroid de Callataÿ, this risala is a summary of Posterior Analytics, the followup to Prior Analytics in the Organum; for Thomas Davidson and Eric van Reijn, this risala concerns rather Aristotle's Physics. Regardless, when the Brethren discuss physics, they employ another hierarchical characterization of the Great Chain of Being: Motion Physical Generation Corruption Augmentation Diminution Alteration Translation Straight Circular Combination Spiritual A summary of Aristotle's de Coelo, with a discussion of astronomy and circumnavigating the kaaba at Mecca A summary of On Generation and Corruption. Sprenger says that it "differs widely from Aristotle's work of the same name. It contains a popular explanation of Aristotle's ideas on the subject, interspersed with numerous moral reflections, and other extraneous matters." On matter, space, motion, and time, according to Aloys Sprenger; Thomas Davidson and Godefroid de Callataÿ list this risala as being on meteorology, using Aristotle's Meteorology; van Reijn simply calls this epistle "The Celestial Bodies". On minerals, which segues into a discussion of souls ascending to heaven A discussion of Nature (the metaphysical entity of the Brethren's hierarchy) and its creation of the animals, plants, and minerals A discussion of the various kinds of plants, and of a quasi-Great chain of being view of the natural hierarchy, in which plants are superior to minerals, but inferior to animals, which are themselves inferior to humans, and thence to angels- and all are inferior to the Creator. The Brethren do not see a clear and sharp break between domains, according the palm tree near-animal status because of its division in male and female sexes. "The Generation of Animals" A discussion and classification of animals. (This was the risala the Rev. T. Thomason first published an excerpt from). "The Composition of the Body." On man's body, and a hermetic view ("As above, so below") view of man's body as a microcosm related to the macrocosm. Ostensibly a summary of the On Sense and the Sensible by Aristotle; it lays out theories of neurology and sensory perception and the effects of astrology on portions of the body. Embryology. Which planets control which month of pregnancy. In spirit, a continuation of the ninth, which begins: "Know, O brother, that the knowledge of one's own self is the key to every science and this is threefold; first, man ought to be acquainted with the component part and economy of his own body, and with all those qualities which are independent of the influences of the soul; secondly, he ought to study the soul and its qualities independent of the body, and thirdly he ought to understand their joint action." The Brethren further go on to lay astrological correspondences with bodily parts and orifices. "On the modalities of birth of the particular souls in the natural human bodily systems." The Institute of Ismaili Studies: The Classification of the Sciences according to the Rasail Ikhwan al-Safa. Davidson offers a clearer gloss: "...shows how the partial soul grows in the human body, and how it may thus, before or after death, become an angel." van Reijn reverses this and the previous one, holding that number 25 is on the embryo and 26 is on "Man as Microcosm".