Concerning the More Certain Fundamentals of Astrology

“Concerning the More Certain Fundamentals of Astrology” by Johannes Kepler is one of the most important historical documents in the evolution of astrology. Written by the legendary astronomer and mathematician who revolutionized planetary theory, this treatise reveals Kepler’s attempt to reform astrology into a scientific, rational, and empirical discipline.

Kepler rejected medieval fortune-telling and symbolic excesses, but he did not dismiss astrology entirely. Instead, he proposed a new foundation based on celestial geometry, harmonic ratios, and planetary aspects—ideas that directly inspired modern harmonic astrology. In this work, Kepler explains which astrological principles he believed were valid, which were superstitious distortions, and how a reformed astrology should function within natural philosophy.

The text covers planetary angles, the physics of celestial influence, the psychology of temperament, and the philosophical basis for cosmic harmony. Kepler argues that planetary aspects express measurable vibrational qualities that correlate with changes in human behavior and natural events—a concept centuries ahead of its time.

This treatise is essential reading for astrologers, historians, astronomers, and esoteric researchers who want to understand astrology through the mind of one of history’s greatest scientific thinkers.

✅ What You’ll Learn:

• Kepler’s critique of medieval and Renaissance astrology
• His philosophical arguments for a reformed, geometry-based astrology
• The origin of harmonic theory and aspect families
• Why Kepler accepted certain aspects and rejected others
• How planetary motion relates to temperament and natural phenomena
• Kepler’s influence on modern astrology, astronomy, and cosmology
• How celestial harmony provides a scientific basis for astrological influence
• Historical context of 17th-century astronomical and metaphysical thought

💡 Key Benefits:

• Understand astrology from the perspective of a scientific revolutionary
• Gain insight into the earliest foundations of harmonic astrology
• Learn which astrological principles survived Kepler’s scientific critique
• Explore the bridge between astronomy, philosophy, and metaphysics
• Strengthen historical and intellectual grounding in astrological theory
• Deepen your understanding of aspects and vibrational geometry

👤 Who This Book Is For:

• Intermediate and advanced astrology students
• Historians of science, cosmology, and metaphysics
• Researchers studying planetary aspects and harmonic theory
• Readers interested in Kepler’s philosophical writings
• Students of esoteric traditions, sacred geometry, and cosmic harmony

📚 Table of Contents:

• Preface
• Kepler’s Critique of Astrology
• The Basis of True Astrology
• Celestial Harmonics
• Planetary Aspects and Geometry
• Psychological and Temperamental Influences
• Astronomical Observations and Method
• Astrology as a Natural Science
• Conclusions

Concerning the More Certain Fundamentals of Astrology By Johann Kepler