Though thus stripped of power, however, the Pythagoreans still maintained themselves for several generations as a social, religious, and philosophical brotherhood. They continued and extended the vein of speculation first opened by the founder himself. So little of proclaimed individuality was there among them, that Aristotle, in criticising their doctrine, alludes to them usually under the collective name Pythagoreans. Epicharmus, in his comedies at Syracuse (470 B.C.) gave occasional utterance to various doctrines of the sect; but the earliest of them who is known to have composed a book, was Philolaus,[24] the contemporary of Sokrates. Most of the opinions ascribed to the Pythagoreans originated probably among the successors of Pythagoras; but the basis and principle upon which they proceed seems undoubtedly his. [Footnote 24: Diogen. Laert. viii. 7-15-78-85. Some passages of Aristotle, however, indicate divergences of doctrine among the Pythagoreans themselves (Metaphys. A. 5, p. 986, a. 22). He probably speaks of the Pythagoreans of his own time when dialectical discussion had modified the original orthodoxy of the order. Compare Gruppe, Ueber die Fragmente des Archytas, cap. 5, p. 61-63. About the gradual development of the Pythagorean doctrine, see Brandis, Handbuch der Gr.-R. Philos. s. 74, 75.] [Side-note: Doctrine of the Pythagoreans--Number the Essence of Things.] The problem of physical philosophy, as then conceived, was to find some primordial and fundamental nature, by and out of which the sensible universe was built up and produced; something which co-existed always underlying it, supplying fresh matter and force for generation of successive products. The hypotheses of Thales, Anaximander, and Anaximenes, to solve this problem, have been already noticed: Pythagoras solved it by saying, That the essence of things consisted in Number. By this he did not mean simply that all things were numerable, or that number belonged to them as a predicate. Numbers were not merely predicates inseparable from subjects, but subjects in themselves: substances or magnitudes, endowed with active force, and establishing the fundamental essences or types according to which things were constituted. About water,[25] air, or fire, Pythagoras said nothing.[26] He conceived that sensible phenomena had greater resemblance to numbers than to any one of these substrata assigned by the Ionic philosophers. Number was (in his doctrine) the self-existent reality--the fundamental material and in-dwelling force pervading the universe. Numbers were not separate from things[27] (like the Platonic Ideas), but _fundamenta_ of things--their essences or determining principles: they were moreover conceived as having magnitude and active force.[28] In the movements of the celestial bodies, in works of human art, in musical harmony--measure and number are the producing and directing agencies. According to the Pythagorean