he shows himself to be thoroughly familiar with the philosophical and scientific literature of the Arabs, and imposes the stamp of his own individuality on the subjects treated. The "Olam Katan" comprises four main divisions, subdivided into sections. After stating the elementary and primary principles of the knowledge of God, the acquisition of which is the highest duty of man, and explaining how the human soul builds up its conception of things, Joseph treats, in the manner of the Arabic Aristotelians, of matter and form, of substance and accident, and of the composition of the various parts of the world. He concludes the first division with the central idea from which the book is evolved, namely, the comparison between the outer world (macrocosm) and man (microcosm), already hinted at by Plato ("Timæus," 47b), and greatly developed by the Arabian encyclopedists known as "the Brethren of Sincerity," by whom Joseph was greatly influenced.