Nor can the gods or stars be said to cause evil on earth, since their influence is affected by other forces which mingle with it. Like the earlier Jewish Platonist, Philo, Plotinus denies that the planets are the cause of evil or change their own natures from good to evil as they enter new signs of the zodiac or take up different positions in relation to one another. He argues that they are not changeable beings, that they would not willingly injure men, or, if it is contended that they are mere bodies and have no wills, he replies that then they can produce only corporeal effects. He then solves the problem of evil in the usual manner by ascribing it to matter, in which reason and the celestial force are received unevenly, as light is broken and refracted in passing through water.[1362] [Sidenote: Against the astrology of the Gnostics.] Plotinus repeats much the same line of argument in his book against the Gnostics, where he protests against “the tragedy of terrors which they think exists in the spheres of the universe,”[1363] and the tyranny they ascribe to the heavenly bodies. His belief is that the celestial spheres are in perfect harmony both with the universe as a whole and with our globe, completing the whole and constituting a great part of it, supplying beauty and order. And often they are to be regarded as signs rather than causes of the future. Their natures are constant, but the sequence of events may be varied by chance circumstances, such as different hours of nativities, place of residence, and the dispositions of individual souls. Amid all this diversity one must also expect both good and evil, but not on that account call nature or the stars either evil themselves or the cause of evil. [Sidenote: Fate and free-will.] As the allusion just made in the preceding paragraph to “the dispositions of individual souls” shows, Plotinus made a distinction between the extent of the control exercised by the stars over inanimate, animate, and rational beings. The stars signify all things in the sensible world but the soul is free unless it slips and is stained by the body and so comes under their control. Fate or the force of the stars is like a wind which shakes and tosses the ship of the body in which the soul makes its passage. Man as a part of the world does some things and suffers many things in accordance with destiny. Some men become slaves to this world and to external influences, as if they were bewitched. Others look to their inner souls and strive to free themselves from the sensible world and to rise above demonic nature and all fate of nativities and all necessity of this world, and to live in the intelligible world above[1364]. [Sidenote: Summary of the attitude of Plotinus to astrology.]