Furthermore, each zodiacal sign has a special relation with a part of the human body.

Furthermore, each zodiacal sign has a special relation with a part of the human body.

 The 12 signs are further divided into four triplicities, each of which governs one of the four elements. Numerous pairs of opposites (male-female, diurnal-nocturnal, hot-cold, and others), based on the speculations of the followers of Pythagoras, a Greek mystical philosopher of the 6th century BC, are connected with consecutive pairs of signs. Finally, a wide variety of substances in the elemental world and attributes of human character are more or less arbitrarily associated with the different signs. 

These lists of interrelationships provide the rationale for many of the astrologer’s predictions.An individual planet’s influences are related both to its general indications when regarded as ominous in Mesopotamian texts and to the traits of its presiding deity in Greek mythology. But on them are also superimposed the system of the four elements and their four qualities, the Pythagorean opposites, and lists of sublunar substances. 

Furthermore, as in the omens, the modes of the planetary motions are carefully considered, since their strengths are partially determined by their phases with respect to the Sun. Also, they exert a mutual influence both by occupying each other’s houses and by means of conjunction and aspects—opposition (to the 7th) and quartile (to the 4th or 10th) generally being considered bad, trine (to the 5th or 9th) and sextile (to the 3rd or 11th) good. Moreover, as the planetary orbits revolve from west to east, the zodiac rotates daily about the Earth in the opposite sense. From a given spot on the Earth’s surface this latter motion—if the ecliptic were a visible circle—would appear as a succession of signs rising one after the other above the eastern horizon. 

Astrologers regard the one that is momentarily in the ascendant as the first place, the one to follow it as the second, and so on, with the one that rose immediately prior to the ascendant being the 12th. In genethlialogy each place in this dōdecatropos determines an aspect of the life of the native (one born under a particular sign); in other forms of astrology the place determines some appropriate aspect of the sublunar world.Astrologers, then, cast a horoscope by first determining for the given moment and locality the boundaries of the 12 places and the longitudes and latitudes of the seven planets. 

They read this horoscope by examining the intricate geometric interrelationships of the signs and their parts and of the planets of varying computed strengths with the places and each other and by associating with each element in the horoscope its list of sublunary correspondences. Any horoscopic diagram, of course, will yield a vast number of predictions, including many that are contradictory or extravagant. Astrologers thus must rely on their knowledge of the client’s social, ethnic, and economic background and on their own experience to guide them in avoiding error and attaining credibility.