Claudius Ptolemy (Κλαύδιος Πτολεμαῖος) AD 90 – c. AD 168: a mathematician, astronomer, geographer and astrologer lived in Egypt
The Ptolemy's treatise on astrology is known as "Tetrabiblios" ("Four Books") it was the most popular astrological work of antiquity and also had great influence in the Islamic world and the medieval Latin West. I am attaching a link to download a digital copy of a rare English translation of the Tetrabiblos from a 1822 edition preserved for generations on library shelves before it was carefully scanned by Google as part of a project of books digitalization.
This book has survived long enough for the copyright to expire and the book to enter the public domain. A public domain book is one that was never subject to copyright or whose legal copyright term has expired. I believe this is an important starting point for those interested in learning about astrology.
If you are interested in learning more about the ancient science of the sky, its origin, meaning and its practical use in measuring time cycles with its application to stocks and commodity trading you may want to read my book "Wall Street Watchman":
