The Lapidary of Alfonso X: stones, stars and signs of the zodiac

Among the most fascinating manuscripts devoted to stones is the Lapidary that Alfonso X of Castile, known as el Sabio, the Wise, had translated. King from 1252 to 1284, Alfonso sponsored in Toledo and Seville a vast programme of translations from Arabic into Castilian, including works of astronomy, law, history and natural science. The Lapidary combines knowledge of gems with astrological knowledge, in a synthesis with no equivalent in the Latin tradition of the time.

A translation from Arabic

According to the prologue, the main text was translated when Alfonso was still infante, that is, heir to the throne, before he became king. The work was entrusted to the Jewish physician and astronomer Yehuda ben Moshe, assisted by the cleric Garci Pérez. The Arabic original was attributed to an author called Abolays, about whom almost nothing is known for certain, and whom the prologue presents as a scholar devoted to ancient books.

The choice of Castilian rather than Latin is significant. Alfonso wanted to make scientific knowledge accessible in a spoken language, and the translations sponsored by his court contributed decisively to the formation of Castilian prose, providing a technical vocabulary for disciplines that until then had been expressed only in Arabic or Latin.

Three hundred and sixty stones for the degrees of heaven

The first and longest of the lapidaries in the manuscript arranges the stones according to the twelve signs of the zodiac. Each sign is divided into thirty degrees, and each degree corresponds to a stone, for a total of three hundred and sixty. For each stone the text gives its name, place of origin, appearance and virtues, linked to the position of the stars which, according to astrological doctrine, govern its power.

Shorter treatises follow, grouping the stones according to further astrological criteria. Many of the stones described are impossible to identify today: some correspond to real minerals, others are fabulous substances handed down by the Arab tradition, which had in turn gathered and reworked Greek, Persian and Indian sources. The modern reader therefore finds in it a map of the astrological imagination more than a mineralogical catalogue.

The Escorial manuscript

The most important copy, kept in the library of the Monastery of El Escorial, is a richly illuminated codex. Each section is accompanied by medallions with the figures of the zodiac signs and by small scenes showing the gathering or use of the stones. The miniatures also offer rare images of merchants, miners and craftsmen at work. The codex is considered one of the masterpieces of thirteenth-century Castilian illumination and a precious record of the meeting of Christian, Jewish and Islamic cultures in medieval Spain.

The Lapidary of Alfonso X shows a way of thinking about stones different from that of Marbod or Albertus Magnus. Here the gem is valued not only for itself but as a mirror of the sky, a receptacle of the astral forces that the Arab tradition had systematised. The virtues described belong to that vision of the cosmos, now superseded, but the manuscript remains a monument of medieval culture and of the coexistence of different kinds of knowledge.