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Famous Medieval Astrologers: Biographical Spotlights on Notable Figures

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Johannes Ehvass

Welcome, dear reader! Together, we embark on a captivating journey into astrology, a timeless art and science that has accompanied humanity since its earliest days. Each astrological discovery not only mirrors the era and culture it emerged from but also feels like a celestial gift, as if the universe is directly speaking to us. Through these articles, I share with you the profound journey of how astrology has grown and evolved alongside us. Let's explore this cosmic connection that has, for millennia, enriched our understanding of ourselves and the universe around us.


Medieval astrology - Famous astrologers


Throughout the Middle Ages, as astrology permeated various facets of life, certain individuals stood out for their exceptional contributions to this celestial art.

From court astrologers who advised kings and queens to scholars who penned influential texts, these figures left an indelible mark on the trajectory of astrological thought.

This article shines a spotlight on some of the most iconic medieval astrologers and delves into their life stories, contributions, and enduring legacies.

Claudius Ptolemy (100-170 AD)

Life and Background

Claudius Ptolemy was an Egyptian astronomer, mathematician, and astrologer who lived in Alexandria. His work in the second century AD laid the foundations for Western astronomical and astrological practices for centuries to come.

Major Works and Contributions

Ptolemy’s “Tetrabiblos” is a seminal text in the field of astrology, presenting a comprehensive system that combines natural and judicial astrology. It has been the cornerstone of astrological teaching and practice, with its influence spanning across the medieval period into the Renaissance and beyond.


Ptolemy’s work became the gold standard for astrological practice in the Western world. His approach to astrology as a part of a rational and natural order of the cosmos influenced not just astrologers but scholars in various fields of science and philosophy.

Guido Bonatti (c. 1223–1300)

Life and Background

As one of the most renowned astrologers of the 13th century, the Italian Guido Bonatti served at the courts of several Italian city-states. His services were not limited to casting horoscopes; he also advised on political and military strategies based on astrological readings.

Major Works and Contributions

Bonatti’s magnum opus, the “Liber Astronomiae” or “Book of Astronomy,” stands as a comprehensive treatise on medieval judicial astrology. Within its pages, he covers a range of topics from natal astrology to horary and electional astrology, providing insights, techniques, and examples for each.


While facing criticism from religious quarters during his life, Bonatti’s influence persisted. His methods and techniques, especially in horary astrology, continue to resonate with astrologers today. His integration of Arabic astrological knowledge with Western thought solidified his position as a bridge between two rich traditions.

Abraham ibn Ezra (1089–1167)

Life and Background

Born in Tudela, Spain, Abraham ibn Ezra was a polymath excelling in various fields, including astrology, mathematics, and poetry. As a Jew in the Islamic Spain of his time, he was exposed to the rich tapestry of Andalusian knowledge, which greatly influenced his works.

Major Works and Contributions

Ibn Ezra penned numerous astrological treatises. Among them, “The Book of Reasons” critically examined the teachings of Ptolemy, while “The Book of Nativities” delved into natal astrology. He also wrote on electional and horary astrology, providing keen insights into each domain.


As a conduit between Islamic and Christian worlds, ibn Ezra played a pivotal role in transmitting Arabic astrological knowledge to Europe. His commentaries and critical examinations of foundational texts provided fresh perspectives and remain influential in contemporary astrological studies.

John of Sacrobosco (c. 1195-1256)

Tractatus de Sphaera (Treatise on the Sphere)

Sacrobosco’s “Tractatus de Sphaera” was a foundational textbook on astronomy in the Middle Ages, widely used in European universities for centuries after its publication. It laid out the basic elements of the Ptolemaic system, which was the prevailing cosmological model that underpinned astrology.

Educational Influence

Because “Tractatus de Sphaera” was a standard educational text, Sacrobosco’s influence spread widely through the academic community, affecting the teaching of both astronomy and astrology. His works helped to standardize and disseminate astrological knowledge within the framework of medieval education.


Sacrobosco’s influence endured well into the Renaissance, making him a key figure in the transmission of astronomical and astrological knowledge from the classical world to the later medieval and early modern periods.

Roger of Hereford (fl. 1176)

Life and Background

Roger of Hereford was an English astrologer and cleric who lived in the 12th century. His work is indicative of the period’s intellectual climate in England, where astrology was pursued in conjunction with other scientific inquiries.

Major Works and Contributions

His translations from Arabic texts and original compositions on astrology contributed significantly to the dissemination of astrological knowledge in medieval England. His work helped to integrate the advanced Arabic astrological science into the Western tradition.


Roger’s contributions helped establish astrology as a respected science in medieval England, influencing the curriculum of educational institutions and the practices of later astrologers.

Hermes Trismegistus

Life and Background

Hermes Trismegistus is a legendary Hellenistic figure, often identified with the Greek god Hermes and the Egyptian god Thoth. He is reputed to be the author of the Hermetic Corpus, a series of texts that are the foundation of Hermeticism.

Major Works and Contributions

The Hermetic texts, particularly those concerned with astrology, have played a crucial role in the development of Western esoteric traditions. These writings address the influence of the stars on the earthly realm and the use of astrology for spiritual ascension.


The philosophy attributed to Hermes Trismegistus has had a profound and enduring influence on Western mystical thought, including Renaissance thinkers who sought to reconcile Hermeticism with Christianity.

Geoffrey Chaucer (c. 1343-1400)

Life and Background

Geoffrey Chaucer, known as the Father of English literature, was also a philosopher, diplomat, and astronomer. He is best known for his literary masterpiece, “The Canterbury Tales.”

Major Works and Contributions

Chaucer’s “Treatise on the Astrolabe” is a didactic work that introduces the use of the astrolabe to a lay audience. It’s one of the earliest technical manuals in English and demonstrates the practical applications of astrology in daily life.


While Chaucer’s literary works overshadow his contributions to astrology, his “Treatise on the Astrolabe” highlights the importance of astrology and astronomical instruments in medieval society and has historical significance as a document of practical science.

Albertus Magnus (c. 1200-1280)

Life and Background

Albertus Magnus, also known as Saint Albert the Great, was a German Dominican friar and bishop who became famous for his comprehensive knowledge of the natural sciences, philosophy, and theology.

Major Works and Contributions

Albertus Magnus wrote extensively on a variety of scientific and philosophical topics. In the realm of astrology, he explored its relationship with the natural world and the philosophical implications of celestial influences on earthly affairs.


Albert’s works bridged the gap between faith and reason, laying the groundwork for later medieval scholars. His writings on astrology helped to contextualize it within the broader scope of natural philosophy and science.

Lesser-Known Contributors to Medieval Astrology:

  1. Roger Bacon (c. 1214-1294):
    • Contribution: An English philosopher and Franciscan friar who wrote on a variety of scientific subjects, including astrology.
  2. Michael Scot (c. 1175-c. 1232):
    • Contribution: His translations of Arabic astrological texts into Latin helped spread astrological knowledge throughout Europe.
  3. Dante Alighieri (1265-1321):
    • Contribution: While primarily known for his literary work, Dante’s “Divine Comedy” contains many references to the cosmology and astrology of his time.
  4. Johannes de Sacrobosco (John of Holywood):
    • Contribution: Not to be confused with John of Sacrobosco mentioned above, he was another medieval scholar who wrote on astronomy and astrology.
  5. Richard of Wallingford (1292-1336):
    • Contribution: An English abbot and mathematician, he designed an astronomical clock and wrote on astrology and its computations.
  6. Levi ben Gerson (Gersonides) (1288-1344):
    • Contribution: A Jewish philosopher, he wrote “The Wars of the Lord” which includes discussions on astrology and astronomy.
  7. Nicole Oresme (c. 1320-1382):
    • Contribution: A philosopher who wrote on a variety of scientific topics and critiqued some of the astrological practices of his time.
  8. William of Conches (c. 1090-c. 1154):
    • Contribution: His philosophical works discussed the influence of stars on the sublunar world, which was a common theme in medieval astrology.
  9. Cecco d’Ascoli (1257-1327):
    • Contribution: An Italian astrologer and physician who wrote “Acerba,” a poem that incorporates astrological themes and was condemned for heresy.
  10. John Gower (c. 1330-1408):
    • Contribution: A contemporary of Chaucer, his poetry often referenced astrological concepts.

These figures, among others, carried the tradition of astrological study and practice forward throughout the medieval period in Europe, adapting and integrating a mix of inherited wisdom and contemporary scholarship. Each contributed to the preservation and development of astrology, influencing the direction it would take in subsequent centuries.

Johannes & Estel: Renowned authorities in Numerology, Astrology, and the esoteric arts. As the founders of Scandinavia's premier Numerology school, we're delighted to share our insights through this curated series on astrology. Dive in and discover the stars.

The Worlds Most Advanced Numerology Report

Your birthdate reveals your unique life purpose, potentials, talents, weaknesses, and karma in this life.
Your names show what you attract into your life regarding your career, relationships, happiness, money, and success.

Introduction to Astrology

The history of Astrology
Moving beyond deterministic astrology
Foundation of Astrology: Planets, Signs and Houses

Astrology and the Holographic Universe

The Holographic Universe
The Human Psyche as a Mirror to The Solar System
The Human Body as a Mirror to The Star Signs

Astrology Background

Egyptian Astrology
Mayan Astrology
Chinese Astrology
Indian Astrology - Jyotish
Celtic Astrology
Tibetan Astrology

Mesopotamian Astrology

Early Mesopotamian Astrology: The Dawn of Celestial Divination
Enuma Anu Enlil: The Epicenter of Babylonian Celestial Omen Interpretation

Babylonian and Chaldean Astrology

Babylonian and Chaldean Astrology
Chaldean influence and evolution
Chaldean Wisdom: Safeguarding and Transmitting Astrological Knowledge

Hellenistic Astrology

Hellenistic Astrology background
Claudius Ptolemy and Tetrabiblos
Vettius Valens
Dorotheus of Sidon

Persian Astrology

Persian Astrology background
Sassanian Astrology

Late Antiquity and The Transition Period

Late Antiquity and The Transition Period
Hellenistic to Islamic Transition: The Torchbearers of Astrological Wisdom

Islamic Golden Age

Arabian Astrology Background
Arabian Astrology Contributions

Medieval Astrology

Introduction: The Medieval Cosmos
Monastic Preservers: Astrological Knowledge in the Dark Ages
Astrology in Medieval Medicine
Kings, Queens, and Constellations: Astrology in the Medieval Court
The Church and the Stars: A Contentious Relationship
Universities and Scholastic Pursuits: Academic Astrology
Astronomy & Astrology: Tools of the Trade
Medieval Astrological Houses and the Synthesis of Traditions
Transition to the Renaissance: Humanism and the Celestial Arts
Reflections: Medieval Astrology's Echoes in Modern Practice
Astrological Art of the Middle Ages
Famous Medieval Astrologers
Medieval Astrological Texts

Renaissance Astrology

Renaissance Humanism and Astrology
Scientific Advancements and Astrology
The Social Fabric: Astrology in Everyday Renaissance Life
Court Astrologers of the Renaissance
Controversies and Conflicts: Astrology Under Scrutiny
Renaissance Texts and Authors: Continuation of a Tradition
Astrology and Art: Celestial Imagery in the Renaissance
Renaissance Astrological Practices: Evolutions and Innovations
End of the Renaissance: The Gradual Decline of Astrological Influence
Renaissance Astrology's Echo in the Modern World

Enlightenment Astrology

Introduction: The Enlightenment and Astrology
Challenging the Stars: Astrology's Critics during the Enlightenment
Astrology and the New World
Astrology in the 19th Century
The Dawn of Psychological Astrology
Astrology in the 20th Century: A Modern Renaissance
Astrological Associations and Schools
Modern Controversies and Astrology
Astrology and Popular Culture
Astrology and Technology
Current Trends and Future Directions in Astrology
Conclusion: Reflecting on Astrology's Evolution

The Planet Significances

The Sun in Astrology
The Moon in Astrology
Mercury in Astrology
Venus in Astrology
Mars in Astrology
Jupiter in Astrology
Saturn in Astrology
Uranus in Astrology
Neptune in Astrology
Pluto in Astrology
Chiron in Astrology
Black Moon Lilith in Astrology
Pars Fortuna in Astrology
Ceres in Astrology

Houses in Astrology

Introduction to Astrological Houses
The Angular Houses
The Succedent Houses
The Cadent Houses
The 1st House
The 2nd House
The 3rd House
The 4th House
The 5th House
The 6th House
The 7th House
The 8th House
The 9th House
The 10th House
The 11th House
The 12th House
Interaction Between Houses
Derived Houses, House Rulers, and Interceptions
Conclusion: Synthesizing House Knowledge

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