Roger Bacon, the thirteenth-century scientist, is said to have made important discoveries in optics  He was an early advocate of hands-on experimentation, and as a teacher warned his students against relying uncritically on the opinions of authorities  Nevertheless, this did not stop Bacon himself from appealing to authority when it was expedient for his own argumentation
Thus, Bacon' s work on optics should be generally disregarded, in view of the contradiction between his statements and his own behavior
criticizes Bacon's character in order to question his scientific findings