Plotinus and astrology.
Porphyry also tells us in the Life that Plotinus devoted considerable attention to the stars and refuted in his writings the unwarrantable claims of the casters of horoscopes.[1342] Such passages are found in the treatises on fate and on the soul, while one of his treatises is devoted entirely to the question, “Whether the stars effect anything?”[1343] This was one of four treatises which Plotinus a little before his death sent to Porphyry, and which are regarded as rather inferior to those composed by him when in the prime of life. In the next century the astrologer, Julius Firmicus Maternus, regards Plotinus as an enemy of astrology and represents him as dying a horrible and loathsome death from gangrene.[1344]
The stars as signs.
As a matter of fact the criticisms made by Plotinus were not necessarily destructive to the art of astrology, but rather suggested a series of amendments by which it might be made more compatible with a Platonic view of the universe, deity, and human soul. These amendments also tended to meet Christian objections to the art. His criticisms were not new; Philo Judaeus had made similar ones over two centuries before.[1345] But the great influence of Plotinus gave added emphasis to these criticisms. For instance, the point made by him several times that the motion of the stars “does not cause everything but signifies the future concerning each”[1346] man and thing, is noted by Macrobius both in the Saturnalia[1347] and the Dream of Scipio;[1348] while in the twelfth century John of Salisbury, arguing against astrology, fears that its devotees will take refuge in the authority of Plotinus and say that they detract nothing from the Creator’s power, since He established once for all an unalterable natural law and disposed all future events as He foresaw them. Thus the stars are merely His instruments.[1349]
The divine star-souls.
But let us see what Plotinus says himself rather than what others took to be his meaning. Like Plato, who regarded the stars as happy, divine, and eternal animals, Plotinus not only believes that the stars have souls but that their intellectual processes are far above the frailties of the human mind and nearer the omniscience of the world-soul. Memory, for example, is of no use to them,[1350] nor do they hear the prayers which men address to them.[1351] Plotinus often calls them gods. They are, however, parts of the universe, subordinate to the world-soul, and they cannot alter the fundamental principles of the universe, nor deprive other beings of their individuality, although they are able to make other beings better or worse.[1352]
How do the stars cause and signify?
In his discussion of problems concerning the soul Plotinus says that “it is abundantly evident ... that the motion of the heavens affects things on earth and not only in bodies but also the dispositions of the soul,”[1353] and that each part of the heavens affects terrestrial and inferior objects. He does not, however, think that all this influence can be accounted for “exclusively by heat or cold,”—perhaps a dig at Ptolemy’s Tetrabiblos.[1354] He also objects to ascribing the crimes of men to the will of the stars or every human act to a sidereal decision,[1355] and to speaking of friendships and enmities as existing between the planets according as they are in this or that aspect towards one another.[1356] If then the admittedly vast influence of the stars cannot be satisfactorily accounted for either as material effects caused by them as bodies or as voluntary action taken by them, how is it to be explained? Plotinus accounts for it by the relation of sympathy which exists between all parts of the universe, that single living animal, and by the fact that the universe expresses itself in the figures formed by the movements of the celestial bodies, which “exert what influence they do exert on things here below through contemplation of the intelligible world.”[1357] These figures, or constellations in the astrological sense, have other powers than those of the bodies which participate in them, just as many plants and stones “among us” have marvelous occult powers for which heat and cold will not account.[1358] They both exert influence effectively and are signs of the future through their relation to the universal whole. In many things they are both causes and signs, in others they are signs only.[1359]
Other causes and signs than the stars.
For Plotinus, however, the universe is not a mechanical one where but one force prevails, namely, that produced by or represented by the constellations. The universe is full of variety with countless different powers, and the whole would not be a living animal unless each living thing in it lived its own life, and unless life were latent even in inanimate objects. It is true that some powers are more effective than others, and that those of the sky are more so than those of earth, and that many things lie under their power. Nevertheless Plotinus sees in the reproduction of life and species in the universe a force independent of the stars. In the generation of any animal, for example, the stars contribute something, but the species must follow that of its forebears.[1360] And after they have been produced or begotten, terrestrial beings add something of their own. Nor are the stars the sole signs of the future. Plotinus holds that “all things are full of signs,” and that the sage can not merely predict from stars or birds, but infer one thing from another by virtue of the harmony and sympathy existing between all parts of the universe.[1361]