Ptolemy's Tetrabiblos

A systematic astrological treatise that explains how the sun, moon, planets and fixed stars are understood to affect weather, geography and human affairs. It lays out technical vocabulary and procedures—signs, houses, aspects, triplicities, exaltations and terms—then applies them across four parts: foundational principles and methods; climatic and regional forecasts including eclipses and atmospheric phenomena; rules for casting nativities and interpreting birth, temperament, health and longevity; and worked examples with tables and commentary. The work emphasizes a disciplined, observational approach to linking astronomical positions with types and timings of terrestrial events.