The twenty-eight lunar mansions of the Arabic tradition
The manazil al-qamar, the twenty-eight dwellings of the Moon: from Bedouin stars to Islamic astronomy, from the Picatrix to Agrippa and our star names.
The Moon takes a little more than twenty-seven days to return in front of the same stars. Many cultures divided this path into stations, one for each night: the nakshatras of India, the xiu of China and the manazil al-qamar, the «dwellings of the Moon», of the Arabs. The last of these, through medieval translations, reached Europe under the name of lunar mansions and became one of the most characteristic themes of the Western astrological and magical tradition.
From Bedouin stars to astronomy
Before Islam, the peoples of the Arabian peninsula watched the rising and setting of certain stars at dawn, the system known as anwa', to forecast rain and mark the seasons. The lunar mansions were laid over this ancient popular knowledge. Many names refer to well-known stars: al-Thurayya designates the Pleiades, al-Dabaran the star we still call Aldebaran, al-Sharatain the two stars of the horns of Aries.
Astronomers of the Islamic world, between the ninth and eleventh centuries, gave the tradition a mathematical form, dividing the zodiac into twenty-eight equal parts of about twelve degrees and fifty-one minutes each. Al-Biruni, in his work on India, compared the Arabic dwellings with the Indian nakshatras, noting similarities and differences. Meanwhile the philologists and lexicographers who wrote about the anwa' preserved the poetic and agricultural side of the old desert stars.
The Picatrix and the Latin West
In Europe the mansions spread above all through the Ghayat al-hakim, «The Goal of the Sage», a vast treatise on astral magic probably composed in Arabic in the eleventh century and translated at the court of Alfonso X of Castile, first into Castilian and then into Latin, under the title Picatrix. It assigned to each mansion a favourable or unfavourable character for various kinds of undertakings, together with images to be engraved on talismans.
In the Renaissance Cornelius Agrippa took up the list in the second book of De occulta philosophia, published in its complete form in 1533, and interest in the mansions passed into treatises on electional astrology. The very name Picatrix, of uncertain origin, became almost a byword for forbidden knowledge. These sources do not teach the astronomy of the Moon, but they show how Europe received and transformed a body of knowledge born among the shepherds and merchants of Arabia.
Twenty-eight names between sky and language
The mansions preserve a small linguistic treasure. Al-Butain means «the little belly», al-Haq'a «the white spot» on the head of Orion, al-Jabha «the forehead» of the Lion, al-Zubana «the claws» of the Scorpion, al-Qalb «the heart», that is, the red star Antares. Some of the brightest stars in our sky owe their modern names precisely to these designations, which reached Europe with medieval astronomical tables and have remained in use to this day.
The number twenty-eight, close to the length of the sidereal month, also had a symbolic fortune. It was the number of letters in the Arabic alphabet, and some authors linked the two, assigning a lunar dwelling to each letter. This pairing of writing and sky, attested in mystical speculation, for instance in Ibn Arabi between the twelfth and thirteenth centuries, shows how far the Moon was understood as an orderer of time and even of language.
The twenty-eight mansions are today a chapter of cultural history rather than a technique. They tell of the continuity between the wisdom of nomads, the astronomy of Baghdad and Cairo, the Iberian courts and the scholars of the Renaissance, and they remind us that for centuries the Moon was the first calendar visible to anyone who raised their eyes to the night sky.