 According to a tradition, the encyclopedia, possibly written in the Near East in the first half of the 9th century by a still unknown author (maybe Abu-l Qasim Maslama al-Majriti, d. 964: see Carusi 2000, 500–502), was known in Spain around 1050; as a matter of fact, there might be some traces of its influence on Solomon Ibn Gabirol (Avicebron, 1021–1058 or 1070), one of the most well-known Medieval Jewish philosophers, living and working in Andalusia in the first half of the 11th century. According to Jacques Schlanger (see Schlanger 1968, 94–97), Ibn Gabirol might have taken from the Brethren of Purity the correspondence between the hierarchy of the beings and the series of the first ten numbers, as well as the reference to the doctrine of some sages about the necessity to “cultivate” our souls through the study of celestial things. According to Georges Vajda (see Vajda 1947, 24–33), more relevant traces might be found in chapter two of the Introduction to the Duties of the Hearth (Hidaya ila fara’id al-qulub), written by the Spanish Jewish author Bahya Ibn Paquda in the period 1050–1080, where there might be some agreements with the Brethren’s cosmological doctrines, as well as a very similar style in defending them. As a matter of fact, both these cases do not prove a direct use of the Brethren’s work by these two Jewish philosophers. The first sure traces of a direct influence of the doctrines of the Brethren of Purity are found in two works written in two different Spanish areas in Judaeo-Arabic (the language of Jews living in Arabic countries) around 1130, and possibly influencing each other: the Book of Microcosm (Kitab al-‘alam al-sagir) by Joseph Ibn Zaddiq (d. 1149), and the Treatise of the Garden by Moses Ibn Ezra. The original text of the work by Joseph Ibn Zaddiq, a rabbinical judge living in Cordoba, is lost, but an anonymous Medieval Hebrew translation is still preserved in some manuscripts, and has been published twice. It includes a number of evident but not literal references to the doctrines of the Brethren of Purity (see Vajda 1949), and its relationship to them was implicitly admitted by the author himself at the very beginning of his work, as follows: “It seems to me that the way for arriving to this great and terrible knowledge (i.e. that of theological truths) consists in understanding the books written by the pure philosophers and the divine sages” (Horovitz 1903, 3). Moreover, in his letter to Samuel Ibn Tibbon Maimonides explicitely affirmed: “I have not read Joseph Ibn Zaddiq’s Microcosm, but I know the author, his value and the value of his book: surely he follows the ideas of the Brethren of Purity” (Marx 1934–1935, 379) – an affirmation which, according to Sarah Stroumsa, should be interpreted as a substantial critique to Ibn Zaddiq’s philosophical views (Stroumsa 1990). As for Moses Ibn Ezra, his Treatise of the Garden is clearly full of references to passages and doctrines indirectly inspired by, and in some cases literally taken from the Brethren of Purity. As recently shown by Paul Fenton in his book about the contents of Ibn Ezra’s work (Fenton 1997; see also Fenton 1976, 297), the Treatise of the Garden includes at least thirty-six passages of the Epistles of the Brethren of Purity, as well as a number of cases where their influence appears to be rather evident. For example, the Brethren of Purity clearly influenced Ibn Ezra’s doctrines about the creation of the world from the First Intellect and the procession of the beings from God to matter, about nature as a power of the Universal Soul, as well as about man as a microcosm. In the same period, even Abraham Ibn Ezra, the well-known Spanish Jewish author and scientist active in Italy, France and England in the period 1140–1160, knew and employed the Brethren of Purity (see Jospe 1994, 46–48).