The following is a brief description of Medieval Astrology (that practised from roughly 750 to 1500 AD), its origins, and the changes in political, religious and sociological climate which have resulted in its transformation from high science and true Occult Art to a practice which is almost unrecognisable, even to some of its foremost practitioners of the present day.
The Astrology of the Greek speaking philosphers of the 1st to 6th Centuries A.D. found its roots in an astral omen lore reaching back to before the birth of Christ and passed down from Egyptian, Babylonian and Persian sources. By 4th Century A.D., astrology was not only recognised as a science, but also influenced most religions in the Roman Empire. The decline of Astrology in the Eastern and Western Roman Empire over the next two centuries coincided, around 7th Century, with the Moslem Arabs' recognition of the importance of science, causing the absorption of Greek Astrology/Science into their own science.
It was not until around 1100 A.D., when the Western Europeans were awakened to this same need for science, that these Arabic translations of the original Greek texts were further translated into Latin. The Byzantine interest in Astrology also revived around this time and there hence remained a strong interest throughout Europe until the time of the Renaissance (15th - 16th Century). During this time the pro-Greek, anti-Oriental sentiment, brought on by the threat from Turkish expansionism, led to a purging of all things Arabic and a strong leaning towards Greek Astrological sources.
In the 17th Century, the Scientific Revolution in Western Europe gave birth to a perception that reason and experimental science alone would soon provide a solution to all of life's mysteries. Copernicus' theory on Heliocentricity led to major doubts about the authenticity of predictive Astrology, whose astronomical basis lay in Ptolemy's Geocentric model, and this type of Astrology all but died out in the latter half of the 17th Century. It did however continue in England where it met some resistance during the 'Age of Reason' in the 18th Century, when astrologers were required to formulate their Art as a Science. This led to a two-way split in Astrology - the Scientific half attempting in vain to mould their Art into a mainstream science, and the Hermetic Astrologers continuing unchecked, resulting in Astrology's relegation to a status of 'Superstition'.
Prior to this, Astrologers were highly learned and worked for both the church and the Aristocracy. However, throughout the 16th - 19th century, due to a growth in the middle classes, a great decline in the power of the Roman Catholic Church, and a near erradication in the nobility, Astrology became much more accessible to the masses and this revolutionised the astrologer's role and modified his Art to suit popular demand.
At the beginning of the 19th Century, when the ability of reason to solve all of man's problems and all of life's mysteries was being increasingly doubted, there was a revival of interest in Astrology and other Occult arts in France and Germany. Unfortunately, there were few Astrologers with the linguistic and mathematical skills necessary to read the important texts. At this time there were two schools of thought: The Rationalist Materialists held that since reason could not discover the transcendent, this could simply be ignored, while the Transcendentalists believed that the Transcendent could be reached via an intuitive faculty, and sought to explore various mental phenomena, leading almost to a merge between Psychology and Astrology. So it was that Astrology in 19th Century England became a kind of vehicle for the propagation of an alternative culture of social, medical and political thought. Darwin's theories on the biological and physiological evolution of man were extended by Herbert Spencer to the sociological and psychological, an important development as some modern-day Astrologers would attribute the lack of ability to predict actual events to this latter type of evolution, seeing Astrology as a tool for describing only potentials and not actuals.
In the last Century Astrology had almost completely removed its interest from the objective study of what is and prediction of what will be, to an evangelistic treatment of what ought to be. In the last quarter of the 20th Century, thanks to such learned Scholars as Robert Zoller, Rob Hand and Robert Schmidt, there has been a recovery in Medieval Astrology and, in part facilitated by recent changes in the Western Academic world, Astrology is now slowly edging its way back to its rightful place in mainstream study.
There are some basic differences between the methods of Modern and Medieval Astrology and these are mainly that the latter makes use of: only the seven visible planets, the Moon's Nodes, fixed stars and Arabic parts; only the ptolemaic aspects; five levels of dignity, while the former uses (at most) two; specific rules guiding delineation; various predictive techniqus unused by the former. In addition, the latter may be considered somewhat 'fatalistic', since it holds firm the idea that the native can do nothing to change the events and circumstances promised by his/her horoscope, the delineation of which is clear-cut, well-defined and nothing to do with psychological evolution.