Ptolemy - Astronomer-Astrologer

A Major Player in the History of Astrology

Ptolemy - Many principles that are used in modern astrological practice were established by Claudius Ptolemaius (called Ptolemy, c100-178AD).

Claudius Ptolemaius was the most important astronomer-astrologer of his day and his work combined the ideas of the Egyptians, Chaldeans, Babylonians, and the Greeks, Pythagoras and Pluto.

His classic work on astrology, Tetrabiblos (four Astrology books), dealt with the control of human life by the stars. This book was an important contribution to astrology and was used to make predictions during his time.

He believed that a certain force is diffused from the heavens over all things on earth. He thought that, although it was difficult to predict events which affect individuals, the applications of astrology should not be rejected.

Although he did not construct the modern type of horoscopes, he was the first mathematician to work on the idea of a system of astrological houses.

Devised A Classification of Human Events
Into 12 Different Astrological Houses

In the second century A.D., he devised the 'Equal House System' (modus equalis), which divided the horoscope into 12 equal segments. Each segment, or cusp, was determined by adding 30-degree increments of longitude to the previous cusp, beginning with the ascendant.

When an individual's horoscope chart is constructed, there will be one of the signs of the Zodiac rising over the east horizon. This is referred to as the ascendant.

In his Tetrabiblos (four Astrology books), he presented this house system as a set of divisions that relate to the stages of life of an individual.

This classification of human events into 12 different groups, each group being associated with a particular astrological house, has proven to be a substantial base for all Western Astrology to this day.

Exactly how and why each of the 12 houses became associated with one particular area of a person's life, still remains a mystery.

Most Popular Astrology Resources

• Ancient Astrology


• Astrological Psychology


• Carl Jung


• Ptolemy - Astronomer/Astrologer


• Astrological Calendar


• Zodiac Circle


• Ophiuchus


• Personal Astrology Reports