orbits of the stars. The authors enter at some length on the sidereal period, or Yugas of the Hindus, which became known to the Arabs by a translation of the Siddhanta." Love of the soul for the Creator. Resurrection and immortality of the soul; this risala has especial emphasis on the ascension of the soul, and Davidson says: "In this the whole system laid down in the Cyclopaedia culminates." On motion, and on the Cosmological argument On cause and effect "On the nature of simple and compound bodies." (Or possibly "On definitions and descriptions", which is followed by van Reijn's translation as "Definitions and Classifications"; Davidson: "...treats of Definitions and Determinations, and tries to show the ideal essence of things, simple and compound.") Theological Sciences A lengthy epistle discussing the various disputing philosophies and religions. Concludes that all aim at the salvation of humans, but non-Islamic ones miss the mark. "The Ascent to God". A discussion of how to reach the Creator through a virtuous and pious life, and how some were called by Him to aid the rest in seeking him. The manner of seeking is also described; the only thing pure in man in his soul, so it is the Soul that one must seek the creator through, however slowly must needs be & they will be judged on their progress. "The Creed [or Doctrine] of the Sincere Brethren". An epistle of stories and parables which explain the religious beliefs of the Brethren; death and pain must be spurned for higher and greater things, ignorance must be vanquished, and examples are given from the lives of Jesus, Mohammed, Socrates, Abraham and others to show that they too believed in another greater life, which one must strive to reach. "On the social intercourse of the Brethren of Purity; on the mutual assistance which they rendered each other in the spirit of true charity; on their benevolence, affection and kind-heartedness. The object of this treatise is to inculcate unity, and the duty of aiding each other in worldly and spiritual concerns." or more simply, "On Friendship". A chapter discussing the Brethren's organization and habits (i.e. meeting for purposes of education, assist one's comrades etc.), whose title van Reijn gives as "Friendship and Mutual Assistance", which is the source for the popular belief that the Brethren derived their name from a story in the Kalilah wa-Dimnah concerned precisely with friendship and