Saint Luke (c.72) - Catholic patron saint of physicians and surgeons (himself being a physician, iconographer and evangelist)
Bede, the Venerable (c.672–735) - Catholic monk who wrote a work On the Nature of Things, and several books on the mathematical / astronomical subject of computus, the most influential entitled On the Reckoning of Time. He made original discoveries concerning the nature of the tides and his works on computus became required elements of the training of clergy, and thus greatly influenced early medieval knowledge of the natural world.
**Pope Silvester II **(c.950–1003) - A scientist and book collector, he influenced the teaching of math and astronomy in church-run schools, and raised the cathedral school at Rheims to the height of prosperity.
Hermannus Contractus (1013–1054) - Wrote on geometry, mathematics, and the astrolabe. He was also a monk who composed Marian antiphons and was essentially beatified.
Robert Grosseteste (c.1175–1253) - Bishop of Lincoln, he was the central character of the English intellectual movement in the first half of the 13th century and is considered the founder of scientific thought in Oxford. He had a great interest in the natural world and wrote texts on the mathematical sciences of optics, astronomy and geometry. He affirmed that experiments should be used in order to verify a theory, testing its consequences.
**Pope John XXI **(1215–1277) - He wrote the widely used medical text Thesaurus pauperum before becoming Pope.
Albertus Magnus (c.1193–1280) - Patron saint of scientists in Catholicism who may have been the first to isolate arsenic. He wrote that: “Natural science does not consist in ratifying what others have said, but in seeking the causes of phenomena.”
Roger Bacon (c.1214–1294) - He was an English philosopher who emphasized empiricism and has been presented as one of the earliest advocates of the modern scientific method. He joined the Franciscan Order around 1240, where he was influenced by Grosseteste. Bacon was responsible for making the concept of “laws of nature” widespread, and contributed in such areas as mechanics, geography and, most of all, optics.
Theodoric of Freiberg (c.1250–c.1310) - Dominican who is believed to have given the first correct explanation for the rainbow in De iride et radialibus impressionibus or On the Rainbow.
Thomas Bradwardine (c.1290–1349) - He was an English archbishop, often called “the Profound Doctor”. He developed studies as one of the Oxford Calculators of Merton College, Oxford University. These studies would lead to important developments in mechanics.
Jean Buridan (1300–1358) - Catholic priest and one of the most influential philosophers of the later Middle Ages. He developed the theory of impetus, which was an important step toward the modern concept of inertia.
Nicole Oresme (c.1323–1382) - Theologian and Bishop of Lisieux, he was one of the early founders and popularizers of modern sciences. One of his many scientific contributions is the discovery of the curvature of light through atmospheric refraction, he also showed that the reasons proposed by the physics of Aristotle against the movement of the Earth were not valid. Oresme strongly opposed astrology and speculated about the possibility of extraterrestrial life.
Nicholas of Cusa (1401–1464) - Cardinal and theologian who made contributions to the field of mathematics by developing the concepts of the infinitesimal and of relative motion. His philosophical speculations also anticipated Copernicus’ heliocentric world-view.
**Ignazio Danti **(1536–1586) - Bishop of Alatri who convoked a diocesan synod to deal with abuses. He was also a mathematician who wrote on Euclid, an astronomer, and a designer of mechanical devices.
René Descartes (1596–1650) - Descartes was one of the key thinkers of the Scientific Revolution in the Western World. He is also honoured by having the Cartesian coordinate system used in plane geometry and algebra named after him. He did important work on invariants and geometry.
Giovanni Battista Riccioli (1598-1671) - Italian astronomer. He was a Jesuit who entered the order in 1614. He was also the first person to measure the rate of acceleration of a freely falling body.
Athanasius Kircher (1602-1680) - German Jesuit scholar who published around 40 works, most notably in the fields of oriental studies, geology and medicine. He made an early study of Egyptian hieroglyphs. One of the first people to observe microbes through a microscope, he was thus ahead of his time in proposing that the plague was caused by an infectious microorganism and in suggesting effective measures to prevent the spread of the disease. Kircher has been compared to Leonardo da Vinci for his inventiveness and the breadth and depth of his work