Michael Servetus, born in Spain most likely on September 29, 1511; his patron saint's day, was a Spanish (Aragonese) theologian, physician, and humanist.

His interests included many sciences: astronomy and meteorology; geography, jurisprudence, study of the Bible, mathematics, anatomy and medicine. He is renowned in the history of several of these fields, particularly medicine and theology.

Servetus was very gifted in languages and studied Latin, Greek and Hebrew. At the age of fifteen, Servetus entered the service of a Franciscan friar by the name of Juan de Quintana, an Erasmian and read the entire Bible in its original languages from the manuscripts that were available at that time. He later attended the University of Toulouse in 1526 where he studied law. There he became suspect of participating in secret meetings and activities of Protestant students.

Servetus built a theology which maintained that the belief of the Trinity was not based on biblical teachings but rather on what he saw as deceitful teachings of Greek philosophers. In part he hoped that the dismissal of the Trinitarian dogma would also make Christianity more appealing to Judaism and Islam which had remained as strictly Monotheistic religions.

Due to his rejection of the Trinity and eventual execution by burning for heresy, Servetus is often regarded as the first (modern) Unitarian martyr. His strong influence on the beginnings of the Unitarian movement in Poland and Transylvania has been confirmed by scholars and two Unitarian Universalist' congregations are named after him, in Minnesota and Washington. A church window is also dedicated to Servetus at the First Unitarian Congregational Society of Brooklyn, NY.

Servetus was the first European to describe the function of pulmonary circulation, although it was not widely recognized at the time, for a few reasons. One was that the description appeared in a theological treatise, Christianizing Restitution, not in a book on medicine. Further, most copies of the book were burned shortly after its publication in 1553. Three copies survived, but these remained hidden for decades. It was not until William Harvey dissections in 1616 that the function of pulmonary circulation was widely accepted by physicians. It is increasingly recognized that the discovery of pulmonary circulation was made 300 years earlier by Ala-al-Din Abu al-Hasan Ali Ibn Abi al-Hazm al-Qarshi al-Dimashqi (known as Ibn Al-Nafis) who was born in 1213 A.D. in Damascus.

In 1984, a Zaragoza public hospital changed its name from José Antonio to Miguel Servetus. It is now a university hospital. Most Spanish cities also include at least a street, square or park named after Servetus. (thanks to Wikipedia for your help)