Robert Grosseteste (c.1170-1253)

Christians who Changed their World

This is part of an on-going series of articles about largely unknown Christians who had an enormous impact on society by faithfully living out their biblical worldview in various areas of life.

Platonic humanism, the worldview that arose in the cathedral schools of the twelfth century, was built around the idea that the world came from God and therefore studying the world can lead us back to God. This idea had implications for a wide range of fields, some of which were mentioned in the article on the Naumburg Master.

Platonic humanism also was connected to the rise of medieval science. “Medieval science” may sound like an oxymoron, but the middle ages saw a number of important advancements in science that laid the foundation for the discoveries of the scientific revolution.

One of the key figures in the early phases of medieval scientific advancement was the unfortunately named Robert Grosseteste. (His last name can be translated “fat head.”) Grosseteste came from a humble background to rise to be an important church statesman, theologian, educator, and eventually bishop of Lincoln, where he is buried.

We know surprisingly little with any degree of certainty about Grosseteste’s education and early career. He was educated in a cathedral school, possibly at Hereford. He showed such ability in the liberal arts, canon law, and even medicine that in 1192, Gerard of Wales recommended him for a position to William de Vere, bishop of Hereford. Grosseteste worked for de Vere until the latter’s death in 1198, after which Grosseteste disappears from the historical record for a while.

In 1255, he was given a benefice in the diocese of Lincoln, and in 1229 became an archdeacon at Leicester and a canon of the cathedral at Lincoln, the largest diocese in England. (Canons were the priests who elected the bishop.) After a serious illness in 1232, which he thought was divine judgment for holding multiple offices, he resigned from his benefice and as archdeacon, keeping only his office as canon.

In 1229, he also began teaching theology at the Franciscan convent in the relatively new University of Oxford, which was in the diocese of Lincoln. His teaching would have a major influence on Franciscan theology for the next century.

In 1235, when Bishop Hugh de Wells of Lincoln died, the canons split over who should be the next bishop. Grosseteste was elected as a compromise candidate, and spent the next 18 years until his death as the bishop of Lincoln.

Once elected bishop, Grosseteste became heavily involved in ecclesiastical politics. He was very concerned about church leadership and problems of corruption in the clergy. Among other things, he got into a conflict with the Archbishop of Canterbury, Boniface of Savoy. This conflict brought Grosseteste before Pope Innocent IV in 1250, where at the age of 80 he lectured Innocent about the problems in the church and laid the blame squarely at the feet of the papacy.

For our purposes, however, it is his work as a theologian and educator that is Grosseteste’s most important contribution to the church. He continued his scholarly work at the University and oversaw its teaching even while involved in his reform program. His theological treatises and teaching shaped Franciscan thought as well as laying the foundation for theology at Oxford more generally. His work on ecclesiology would be a major influence on the English Reformer John Wyclif a century after Grosseteste’s death.

Along with producing a number of important theological treatises, Grosseteste also learned Greek and translated the theology of John of Damascus and the entire corpus of Pseudo-Dionysius (a major influence on medieval mysticism) into Latin.

In addition to his work on formal theology and his translations, Grosseteste had a major impact on the development of medieval science, both in terms of methodology and content.

Grosseteste was the one of the first medieval thinkers to understand Aristotle’s approach to studying the natural world, an approach which he called “resolution and composition.” This was an early version of the scientific method. It begins with observation of particulars, which leads to the formulation of a universal law that governs the particulars (“resolution”). This law is then used to make predictions about other particulars (“composition”). Both resolution and composition need to be verified through experimentation and additional observation, not through pure logic.

Grosseteste’s methodology would continue to shape natural philosophy (i.e. studies of the natural world) into the seventeenth century and the beginnings of the scientific revolution, including influencing Galileo.

Another important element of Grosseteste’s thought was idea that sciences followed a hierarchical order. For example, optics depends on geometry; this means that geometry is foundational for optics and thus that optics is subordinate to geometry.

More generally, Grosseteste followed the late Roman writer Boethius in arguing that since the natural sciences are based on mathematics, mathematics is the highest of the sciences. Although the role of mathematics in the sciences is widely understood today, Grosseteste’s rediscovery of that truth made it a principle in medieval natural philosophy that then carried over to the founders of modern science.

In the realm of natural science, Grosseteste was particularly interested in optics, a fascination which he also passed on to the next generation of Franciscan theologians. Of all the topics included in natural philosophy, optics was seen as being particularly important because it had the closest connection to epistemology, the branch of philosophy that deals with knowledge.

Following St. Augustine of Hippo, Grosseteste argued that the only way we can know truth was through illumination. He used the workings of physical light to explain this: just as we cannot see a body unless it has light shining on it, so the mind cannot comprehend truth unless divine light illuminates it. This divine light is none other than the logos, Jesus, the Light of the World. All knowledge of truth, for Christian and non-Christian alike, is mediated by Christ through the process of divine illumination.

For Grosseteste, understanding light had much greater significance even than its application to epistemology. Grosseteste believed that Gen. 1 taught that light was the first element of creation, and thus that light was the basis from which everything else was made. In fact, light was at the foundation of Grosseteste’s entire cosmology, as well as his understanding of the relationship between soul and body.

Along with his use of light throughout his speculative philosophy, Grosseteste also studied it as a physical phenomenon. He worked with spherical glass bowls filled with water, lenses, and other tools to explore the behavior of light, and made significant advances in optics that would lead over the next years to the development of eyeglasses, among other things. Some scholars today even suggest that he had a very modern understanding of how color works centuries before Isaac Newton would demonstrate the visible spectrum in white light.

Grosseteste’s work married philosophical and theological reflection, mysticism, and observation and experimentation in the natural realm to produce a highly integrated vision of the world that is foreign to the way we think today. His groundbreaking work in scientific methodology, in mathematizing natural philosophy, and the specific conclusions he reached with regard to optics were important advancements in knowledge in the middle ages that had a profound influence on his students and on theology and natural philosophy for the next several centuries.


Dr. Glenn Sunshine is a professor of history at Central Connecticut State University and a Senior Fellow at the Colson Center for

Comment Policy: Commenters are welcome to argue all points of view, but they are asked to do it civilly and respectfully. Comments that call names, insult other people or groups, use profanity or obscenity, repeat the same points over and over, or make personal remarks about other commenters will be deleted. After multiple infractions, commenters may be banned.