Pedro Ciruelo

Pedro Sánchez Ciruelo (c. 1465 – 1548) was a Spanish philosopher, theologian, mathematician, astrologer, astronomer and writer on topics of natural philosophy.

Early life Ciruelo was born somewhere between 1460 and 1470 in Daroca, Spain. Ciruelo was born in the kingdom of Aragon where Daroca held political, military, and administrative significance for the kingdom. Gaspar Lax, Miguel Francés, Jacobo Ramírez, and Alfonso Osorio became part of a circle of Spanish calculatores interested in mathematical physics and the works of Oxford Calculatores.

Ciruelo also published a number of books during his tenure through the French printer and publisher Guy Marchant.

Works and beliefs Ciruelo wrote a commentary on the Sphaera de Sacrobosco, and on Thomas Brawardine's mathematical works Arithmetica Speculativa and Geometria Speculativa, among others. helping to solidify Paris' role in the 15th-century mathematics book market. At the time there was no standardized curriculum for mathematics at the University of Paris. Ciruelo is one of few known sources discussing this history. These writings were exemplary of the "arithmetization of geometry" taking place in mathematics during the 16th century. Ciruelo believed that knowing the cosmos was a way of admiring God's creation, and the use of amulets, horoscopes and rain making, but considered the flights of witches to be real.

The supernatural order refers to events caused by God's intervention, which take the form of miracles. As Ciruelo puts it, "[the supernatural] comes from God, who operates miraculously on the course of nature". The preternatural order refers to events caused by the intervention of spirits, demons, and angels in the natural world. These entities were created by God and, although having supernatural powers, were still considered natural beings. This combination of the natural and the supernatural necessitates a middle ground between them: the preternatural. The natural order refers to events caused by beings and materials in the 'sublunar sphere' -- that is, here on earth. According to Ciruelo, the third order usually takes the form of actions committed by free-willed, living creatures.

Ciruelo believed that these three orders were the only categories needed to explain events on earth. The natural and supernatural orders were originally proposed by Anselm of Canterbury, but Ciruelo eventually added the preternatural order, seeing it to be a natural consequence of the other two. This extra distinction between the natural and the supernatural outlined the futility of superstitious rituals, in Ciruelo's view. Rituals seeking to accomplish preternatural feats would, by nature of being an invented by humanity, never be able to come to fruition without the help of some preternatural or supernatural power.

It is for these reasons that the only astrology Ciruelo considered to be "legitimate" was "natural astrology;" that is, the astrological practices that respected the boundary between the natural and the preternatural.

Publications 1495. . Paris: Guy Marchand. (reprinted Paris, 1502). 1495. . Paris: Jean Petit. (reprinted 1502, 1508, 1511, 1530). 1495. . Paris: Guy Marchand. (reprinted 1502, 1505, 1509, 1513, 1514). 1498. . Paris: Jean Petit. 1508. . Paris: Jean Petit. 1515. . D. Paris: Jean Petit. 1516. Cursus quattuor mathematicarum artium liberalium. Alcalá: Arnaldo Guillén Brocar. This work was reprinted in Alcalá in 1526 and 1528. 1519. . Alcalá: Arnaldo Guillén Brocar. 1521. Apotelesmata astrologiae Christianae. Alcalá de Henares: Juan de Eguía. 1526. Opusculum de sphera mundi Joannis de sacro busto: cum additionibus: et familiarissimo commentario Petri Ciruelli Darocensis: nunc recenter correctis a suo autore: intersertis etiam egregijs questionibus domini Petri de Aliaco. Alcalá de Henares: Miguel de Eguía. 1528. . Alcalá: Miguel de Eguía. (two new editions in 1529). 1538. Reprobación de supersticiones y hechicerías. Medina del Campo: Guillermo de Millis. (reprint in 1551)