In another treatise on _Diagnosis from Dreams_ Galen makes a closer approach to the arts of divination.[832] He states that dreams are affected by our daily life and thought, and describes a few corresponding to bodily states or caused by them. He thinks that if you dream you see fire, you are troubled by yellow bile, and if you dream of vapor or darkness, by black bile. In diagnosing dreams one should note when they occurred and what had been eaten. But Galen also believes that to some extent the future can be predicted from dreams, as has been testified, he says, by experience.[833] We have already mentioned the effect of his father’s dream upon Galen’s career. In the Hippocratic commentaries[834] he says that some scorn dreams and omens and signs, but that he has often learned from dreams how to prognosticate or cure diseases. Once a dream instructed him to let blood between the index and great fingers of the right hand until the flow of blood stopped of its own accord. “It is necessary,” he concludes, “to observe dreams accurately both as to what is seen and what is done in sleep in order that you may prognosticate and heal satisfactorily.” Perhaps he had a dim idea along Freudian lines. [Sidenote: Lack of astrology in most of Galen’s medicine.] In the ordinary run of Galen’s pharmacy and therapeutics there is very little mention or observance of astrological conditions, although Hippocrates is cited as having said that a study of geometry and astronomy—which may well mean astrology—is essential in medicine.[835] In the _De methodo medendi_ he often urges the importance of the time of year, the region, and the state of the sky.[836] But this expression seems to refer to the weather rather than to the position of the constellations. The dog-star is also occasionally mentioned,[837] and one passage[838] tells how “Aeschrion the Empiric, ... an old man most experienced in drugs and our fellow citizen and teacher,” burned live river crabs on a plate of red bronze after the rise of the dog-star when the sun entered Leo and on the eighteenth day of the moon. We are also informed that many Romans are in the habit of taking theriac on the first or fourth day of the moon.[839] But Galen ridicules Pamphilus for his thirty-six sacred herbs of the horoscope—or decans, taken from an Egyptian Hermes book.[840] On the other hand, one of his objections to the atomists is that “they despise augury, dreams, portents, and all astrology,” as well as that they deny a divine artificer of the world and an innate moral law to the soul.[841] Thus atheism and disbelief in astrology are put on much the same plane. [Sidenote: _The Prognostication of Disease by Astrology._]