Pliny tells how the physician Crinas of Marseilles made a fortune by regulating diet and observing hours according to the motion of the stars.[469] But he does not show much faith in astrological medicine himself, rejecting entirely the elaborate classification of diseases and remedies which the astrologers had by his time already worked out for the revolutions of the sun and moon in the twelve signs of the zodiac.[470] In his own recipes, however, astrological considerations are sometimes observed, as we have already seen, especially the rising of the dog-star and the phases of the moon. Pliny, indeed, states that the dog-star exerts an extensive influence upon the earth.[471] As for the moon, the blood in the human body augments and decreases with its waxing and waning as shell-fish and other things in nature do.[472] Indeed, painstaking men of research had discovered that even the entrails of the field-mouse corresponded in number to the days of the moon, that the ant stopped working during the interlunar days, and that diseases of the eyes of certain beasts of burden also increased and decreased with the moon.[473] But on the whole Pliny’s medicine and science do not seem nearly so immersed in and saturated with astrology as with other forms of magic. This gap was for the middle ages amply filled by the authority of Ptolemy, of whose belief in astrology we shall treat in the next chapter. [Sidenote: Conclusion: magic unity of Pliny’s superstitions.] We have tried to analyze the contents of the _Natural History_, bringing out certain main divisions and underlying principles of magic in Pliny’s agriculture, medicine, and natural science. This is, however, an artificial and difficult task, since it is not easy to sever materials from ceremonial or the virtues of objects from the relations of sympathy or antipathy between them. Often the same passage might serve to illustrate several points. Take for example the following sentence: “Thrasyllus is authority that nothing is so hostile to serpents as crabs; swine who are stung cure themselves by this food, and when the sun is in Cancer, serpents are in pain.”[474] Here we have at once antipathy, the remedies used by animals, the reasoning, characteristic of magic, from association and similarity, and the belief in astrology. And this confusion, to illustrate which a hundred other examples might be collected from the _Natural History_, demonstrates how indissolubly interwoven are all the varied threads that we have been tracing. They all go naturally together, they belong to the same long period of thought, they represent the same stage in mental development, they all are parts of magic. CHAPTER III SENECA AND PTOLEMY: NATURAL DIVINATION AND ASTROLOGY