Modern academic PDFs (such as those by Roger Beck or Tamsyn Barton) treat horoscopic astrology not as science but as a fascinating historical case study of cultural transmission. They trace how a Babylonian priest’s omen became a Roman emperor’s natal chart and, eventually, a newspaper’s daily "Sun sign."
The earliest surviving horoscopic text is the Tetrabiblos by Claudius Ptolemy (2nd century CE). While Ptolemy wrote in Greek, his work became the Bible of Western astrology. A good PDF will explain that Ptolemy systematized the horoscope using: a history of horoscopic astrology pdf