Bishop Robert Grosseteste

Bishop of Lincoln and Oxford’s founder of scientific thought, he showed how to use experiment to verify a theory. A. C. Crombie calls him “the real founder of the tradition of scientific thought in medieval Oxford, and in some ways, of the modern English intellectual tradition”.

Born around 1175 AD, Robert Grossetest (c. 1175-1253) was a deacon by 1225 and Archdecon of Leicester by 1229, when he began lecturing at Oxford. By 1235, he was consecrated Bishop of Lincoln. He taught the Franciscan Roger Bacon, instilling an interest in the scientific method. Grosseteste’s theological writings considered the natural world a major resource for theological reflection. He is best known as an original thinker for his work on the scientific method. From 1220 to 1235 he wrote a host of scientific treatises including:

• De sphera. An introductory text on astronomy.
• De accessu et recessu maris. On tides and tidal movements. (although some scholars dispute his authorship)
• De lineis, angulis et figuris. Mathematical reasoning in the natural sciences.
• De iride. In On The Rainbow, Grosseteste predicts the invention of the telescope (1608): “This part of optics, when well understood, shows us how we may make things a very long distance off appear as if placed very close, and large near things appear very small, and how we may make small things placed at a distance appear any size we want, so that it may be possible for us to read the smallest letters at incredible distances, or to count sand, or seed, or any sort of minute objects.”  
• De luce. Four centuries before Isaac Newton proposed gravity and seven centuries before the Big Bang theory, Grosseteste’s Of Light described the birth of the Universe as an explosion and the crystallisation of matter to form stars and planets in a set of nested spheres around Earth. De Luce is the first attempt to describe the heavens and Earth using a single set of physical laws. This is easily the most original work of cosmogeny until Newton.

He also wrote a number of commentaries, including commentaries on Aristotle’s Physics, the first western commentary on Aristotle’s Posterior Analytics, and a thorough analysis of Pseudo-Dionysius the Areopagite’s Celestial Hierarchy.

Grosseteste introduced the notion of controlled experiment as one among many ways of arriving at knowledge. Although he did not always follow his own advice, his work is seen as instrumental in the development of the Western scientific tradition. Grosseteste was the first of the Scholastics to fully understand Aristotle’s vision of the dual path of scientific reasoning: generalising from particular observations into a universal law, and then back again from universal laws to prediction of particulars. Grosseteste called this “resolution and composition”. He asserted both paths should be verified through experiment to verify the principles involved. The tradition he established was popularized five centuries later by Galileo Galilei.

Even more important was Grosseteste’s use of the “heirarchy of goods” to order scientific knowledge. For instance, he argued that optics is subordinate to geometry because optics depends on geometry, making optics a subalternate science. Thus, Grosseteste concluded, championed Boethius in arguing that mathematics was the highest of all sciences, and the basis for all others, since every natural science ultimately depended on mathematics. Groesseteste argued that light was the “first form” of all things, the source of all generation (biology) and motion (physics). Since light could be reduced to lines and points, and thus fully explained by mathematics, mathematics was the highest order of the sciences. The ‘Ordered Universe’ collaboration of scientists and historians at Durham University studies medieval science. This team regards Bishop Robert Grosseteste as a key figure who demonstrates that pre-Renaissance science was far more advanced than previously thought.