Porphyry objected that those who thus reduce religion to astrology submit everything to fate and leave the human soul no freedom, and furthermore that in any case astrology is an unattainable science. Iamblichus defends it against these objections, insisting that the universe is divided under the rule of planets, signs, and decans;[1413] that the Egyptians do not make everything physical but ascribe two souls to man, one of which obeys the revolutions of the stars, while the other is intellectual and free;[1414] and that there is a systematic art of astrology based on divine revelation and the long observations of the Chaldeans, although like any other science it may at times degenerate and become contaminated by error.[1415] Iamblichus further regards as ridiculous the contention of those “who ascribe depravity to the celestial bodies because their participants sometimes produce evil.”[1416] In the brief separate treatise, _De fato_,[1417] he again holds that all things are bound by the indissoluble chain of necessity which men call fate, but that the gods can loose the bonds of fate, and that the human mind, too, has power to rise above nature, unite with the gods, and enjoy eternal life. [Sidenote: Porphyry and astrology.] Whether Porphyry in his other extant works evidences a belief in astrology or not, and whether he wrote an _Introduction to the Tetrabiblos_ or astrological handbook of Ptolemy, has been disputed.[1418] This _Introduction_ ascribed to Porphyry was much cited by subsequent astrologers[1419] and was printed in 1559 together with a much longer anonymous commentary on the _Tetrabiblos_ which some ascribe to Proclus.[1420] [Sidenote: Astrological images.] Towards astrological images at least, Porphyry shows himself in the _Letter to Anebo_ more favorable than Iamblichus, saying, “Nor are the artificers of efficacious images to be despised, for they observe the motion of celestial bodies.” Iamblichus, on the other hand, rather grudgingly admits that “the image-making art attracts a certain very obscure genesiurgic portion from the celestial effluxions.”[1421] He seems to have the same feeling against images as against characters, perhaps regarding both as bordering upon idolatry.[1422] [Sidenote: Number mysticism.] Plotinus, Porphyry, and Iamblichus were all given to number mysticism. The sixth book of the sixth _Ennead_ is entirely devoted to this subject, while Porphyry and Iamblichus both wrote _Lives_ of Pythagoras and treatises upon his doctrine of number. [Sidenote: Porphyry as reported by Eusebius.]