List of Rasa'il in The Encyclopedia of The Brethren of Purity - Natural Sciences

Natural Sciences

1. 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
2. A summary of Aristotle's de Coelo, with a discussion of astronomy and circumnavigating the kaaba at Mecca
3. 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."
4. 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".
5. On minerals, which segues into a discussion of souls ascending to heaven
6. A discussion of Nature (the metaphysical entity of the Brethren's hierarchy) and its creation of the animals, plants, and minerals
7. 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. Interestingly, 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.
8. "The Generation of Animals." A discussion and classification of animals. (This was the risala the Rev. T. Thomason first published an excerpt from).
9. "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.
10. 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.
11. Embryology. Which planets control which month of pregnancy.
12. 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.
13. "On the modalities of birth of the particular souls in the natural human bodily systems." . 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".
14. "On the extent of the powers of the human mind to penetrate into the mysteries of the universe" and the mysteries of the Creator.
15. On life and death, and how a rational soul is embodied, and why death is not to be feared, since it allows the good to reach Paradise. (van Reijn likewise reverses this and the preceding one).
16. Pleasure and pain, in mortal and immortal life.
17. "The Diversity of Languages" On the purposes and functions of language, and also on the cause of differing languages.