A zairja (also transliterated za’irajah, zairajah and zairdja) was a device used by medieval Arab astrologers to generate ideas by mechanical means. The name may derive from “a mixture of the Persian words for horoscope, astronomical table”
Ibn Khaldun describes it as: “A branch of the science of letter magic, practiced among the authorities on letter magic, is the technique of finding out answers from questions by means of connections existing between the letters of the expressions used in the question. They imagine that these connections can form the basis for knowing the future happenings they want to know.“ He suggests that rather than being supernatural it works “from an agreement in the wording of question and answer…with the help of the technique called the technique of breaking down.” (ie algebra).
It used the 28 letters of the Arabic alphabet to signify 28 categories of philosophic thought. By combining number values associated with the letters and categories, new paths of insight and thought were created.
*A manuscript in Rabat recounts Ibn Khaldun’s introduction to the machine by Al-Marjānī in 1370 (772 AH), and claims that it was a traditional and ancient science. When Ibn Khaldun expressed skepticism, the pair asked the instrument how old it was, and was told by the machine it was invented by the prophet Idris (identified with the Biblical Enoch).