Elements of a modern scientific method are found in early Muslim philosophy, in particular, using experiments to distinguish between competing scientific theories and a general belief that knowledge reveals nature honestly. In the Middle Ages, Islamic philosophy developed and was often pivotal in scientific debateskey figures were usually scientists and philosophers.
The Arab physicist Abu Ali Hasan Ibn al-Haitham (more often known in the West as Alhazen) (965-1040 CE) was particularly influential. His work on optics, Kitab-al-Manadhirn, which contained a careful examination of the laws of reflection and refraction, was translated into Latin in the Middle Ages. An important observation in that work led Alhazen to propose that the eyes receive light reflected from objects, rather than emanating light themselves, contradicting contemporary beliefs, including those of Ptolemy and Euclid. The way in which Alhazen combined observations and rational arguments had a great influence on Roger Bacon and Johannes Kepler in particular.
D. C. Lindberg, Theories of Vision from al-Kindi to Kepler, (Chicago, Univ. of Chicago Pr., 1976), pp. 60-7.