"From his own day well into the Renaissance, Claudius Ptolemy's name was well-nigh pre-eminent in astronomy, geography, and astrology. 'The divine Ptolemy' he is called by Hephaestion of Thebes, and the expression shows that the reverence accorded him fell little short of idolatry." (Robbins, Harvard Press - 1940)

Ptolemy wrote the cornerstone of Western Astrology, Tetrabiblos. It is the source of many of the concepts that still guide astrology today. His Tetrabiblos or Four Books layout the general principles of this discipline.

He leaves it to the individual to draw their own conclusions from general principles. He make it clear that interpretation requires conjecture but declines to discuss astrology on that level when he states the following in Book III, Paragraph 108 "...the predicted result, summed up by the combination of many elements, applied to the underlying form, we shall leave, as to the skillful archer, to the calculation of him who conducts the investigation....".

Ptolmey knew that the generations that preceded him (which he calls the ancients) knew how to combine and sythesize the different influences in a chart but deliberately declined to elaborate on the topic knowing it was complex. He says in the same section, "...and furthermore we shall omit it (a discussion on synthesis) on account of the difficulty in using it and following it..."

It was left to Morin (and to others) to build upon and expand at great length the general principles given by Ptolemy with such elegance and clarity.