The ancient doctrine of the Arabic Parts (or "lots") gives the astrologer a profound insight into the inner workings of a horoscope - whether it be natal, mundane, horary or electional. They are arithmetically derived points on the ecliptic which deal with all areas of life -including war, wisdom, commodity speculation, profession, marriage, children, partnerships, death and spirituality.
Until more recent times they have been largely lost to the modern astrologer. But those who have developed a competence in their use find them an invaluable key to delineation and accurate prediction.
The author, Guido Bonatti a thirteenth century professional astrologer, drew upon material produced by outstanding Arabic and Greek antecedents. He adds to their insight his own extensive experience. Used in conjunction with a thorough understanding of the astrological horoscope these Arabic Parts provide the serious astrologer with a profundity of insight otherwise not available.
The translation presented here is the only one available to the English reading public. It deals with that section of Bonatti's famous summa of medieval astrology the Liber Astronomia which unfolds this arcane doctrine. The translator Robert Zoller is a professional astrologer with thirty years experience in the field of medieval astrology.
Just a suggestion. Read this work with the Liber Hermetis (which you should be able to find on here under books). I think that much of what is written in the LH (about the Arabic parts) was what Bonatti (writing centuries later) was drawing upon in his work on the Arabic parts.
Agree with the comment re reading this work with the Liber Hermetis. The Arabic parts (or Greek Lots) seem counter intuitive because they are "derived" from secondary calculations and not based upon standard planetary configurations ie if you look in the sky there is nothing there. But time and again they either give an insight or confirm one that you may have not been sure of. Bonatti and the very good DMA lessons on the Arabic parts concentrate on how to use the parts, their practical application which is essential to understand but it was only when I read the Liber Hermetis that I got a glimmer that they really are occult (as in hidden from general empirically tested understanding) indicators that point to something that is under-pinning astrology, and goes beyond mere planetary movements or fixed stars.