Pope John XXI (Peter of Spain)

c. 1215-1277

Spanish Physician and Pope

Perhaps the most famous of the medieval scientist-popes—men whose contributions to learning were as important as the fact that they held the most powerful throne in Europe—was Sylvester II, or Gerbert (945-1003). Equally noteworthy, however, was John XXI, who for most of his life was known as Peter of Spain. In addition to his Treasury of Medicines for the Poor, Peter wrote a work on optics, along with one of the medieval world's most influential textbooks on logic.

He was born Pedro Julião in Lisbon between 1210 and 1220, and though Portugal by then had established an identity separate from that of its larger neighbor, he would become known as Pedro Hispano, Petrus Hispanus, or Peter of Spain. During the late 1220s and early 1230s, Peter studied at the University of Paris, where his instructors included Albertus Magnus (c. 1200-1280). There he became intrigued by the writings of Aristotle (384-322 b.c.), particularly with regard to the natural sciences, and devoted himself to the study of medicine.

After earning his master's degree, in 1247 Peter was appointed professor of medicine at Siena, Italy, whose university was then newly founded. While at Siena, he wrote Summulae logicales (Small logical sums), destined to remain in wide use for the next three centuries. It may also have been during this period, before church affairs increasingly occupied his time, that Peter wrote Liber de oculo (Concerning the eye).

Beginning in 1261, Peter moved through the ranks of the church's upper echelons, and became a close associate of Teobaldo Visconti (1210-1276). Peter was serving as archdeacon of Vermuy in the Diocese of Braga, Portugal, when Teobaldo left for the Holy Land to accompany King Edward I of England on the Ninth Crusade. At this point the papacy had been vacant for three years, a situation that had a number of repercussions—most notably the fact that Marco Polo (1254-1324) and his father and uncle, in need of an audience with the pope, were forced to stall their departure on their now-celebrated journey. Teobaldo, who met the Polos in Palestine, shortly afterward received the startling news that he was to be the new pope. He rushed back to Italy, where as Pope Gregory X he appointed Peter his personal physician in 1272.

While serving Gregory in this capacity, Peter wrote his Thesaurus pauperum (Treasury of medicines for the poor.) The latter is, as its name indicates, a medical handbook for those who could not afford the care of a physician, and in time it would become a highly popular source of medical knowledge. The book paid special attention to herbal treatments, and despite his role as a priest, Peter even discussed plants a woman might use for contraception, including calamint, costus, pepper, rue, and sage. Elsewhere Peter discussed remedies for a wide variety of bodily ailments.

Though Peter was appointed Archbishop of Braga in the spring of 1273, Gregory soon had him consecrated as bishop. Gregory himself died in 1276, and was followed in quick succession by Innocent V and Adrian V. The latter reigned for only 39 days before dying, and a month later, the College of Cardinals elected Peter as Pope John XXI. (Actually, he was the twentieth pope to use the name John, but due to an error in Vatican record-keeping that went back to the tenth century, there was no John XX.)

As pope, John XXI dealt with a number of foreign-policy issues, including the ambitions of Charles of Anjou to control Italy, as well as conflicts between the English royal house and the papacy. Most intriguing, because of the potential consequences of these events, were his dealings with eastern monarchs. He received delegates from Abaga, Khan of Tartary, who beseeched the pope's assistance in a crusade against the Muslims and asked to have missionaries sent to his Central Asian khanate. Also, the pope received ambassadors from Byzantine emperor Michael Palaeologus, who along with the new patriarch of Constantinople, John Beccus, desired a rapprochement between the eastern and western churches; indeed, both Michael and his patriarch were willing to submit to the pope and the Roman Catholic Church.

But neither the conversion of the Tartars, nor the reunification of the Christian church, was to be: both undertakings were cut short by John's unexpected death. Eager to continue his scientific studies amid the fast-paced life of the papal residence, John (who like Gregory lived in Viterbo rather than Rome), had a special laboratory/apartment built on the back of his living quarters. He was working alone there when on May 14, 1277, the roof caved in on him, and he died six days later as a result of his injuries.

Soon after his death, John's prodigious medical learning made him a target for political enemies, who claimed that the late pope had dabbled in magical arts. His reputation suffered somewhat as a result, but has been rehabilitated in later centuries.

JUDSON KNIGHT