OCEANIC DISCOVERIES. 245 



ical basis, and by the calling forth of phenonf.cna by the pro- 

 cess of experiment, Roger Bacon, the cotemporary of Alber- 

 tus of Bollstadt, may be regarded as the most important and 

 influential man of the Middle Ages. These two men occupy 

 almost the whole of the thirteenth century ; but to Roger Ba- 

 con belongs the merit that the influence which he exercised 

 on the form of the mode of treating the study of nature has 

 been more beneficial and lasting than the various discoveries 

 which, with more or less justice, have been ascribed to him. 

 Stimulating the mind to independence of thought, he severe- 

 ly condemned the blind faith attached to the authority of the 

 schools, yet, far from neglecting the investigations of the an- 

 cient Greeks, he directed his attention simultaneously to phil- 

 ological researches,* and the application of mathematics and 

 of the Scientia experimentalis, to which last he devoted a 

 special section of the Opus Majus^ Protected and favored 

 by one pope (Clement IV.), and accused of magic and impris- 

 oned by two others (Nicholas III. and IV.), he experienced 

 the changes of fortune common to great minds in all ages. 

 He was acquainted with the Optics of Ptolemy,^ and with 



* So many passages of the Opus Majus show the respect whicl Roger 

 Bacon entertained for Grecian antiquity, that, as Jourdain has already 

 remarked (p. 429), we can only interpret the wish expressed by him in 

 a letter to Pope Clement IV., '* to burn the works of Aristotle, in order 

 to stop the diffusion of error amon^ the scholars," as referring to the 

 bad Latin translations from the Arabic. 



t " Scientia experimentalis a vnlgo stadentium penitus ignorata; duo 

 tamen sunt modi cognoscendi, scihcet per argumeiitum et experientiam 

 (the ideal path, and the path of experiment). Sine experientia nihil 

 sufBcienter sciri potest. Argumentum concludit, sed non certificat, 

 neque removet duditationem ; et quiescat animus in intuita veritatis, 

 nisi eam inveniat via experientiie." {Opus Majus, pars vi., cap. 1.) I 

 have collected all the passages relating to Roger Bacon's physical 

 knowledge, and to his proposals for various inventions, in the Examen 

 Crit. de V Hist, de la Geogr., t. ii., p. 293-299. Compare, also, Whe- 

 well, Philosophy of the Inductive Sciences, vol. ii., p. 323-337. 



X See ante, p. 194. I tind Ptolemy's Optics cited in the Opus Ma- 

 jus (ed. Jebb, Lond., 1733), p. 79, 288, and 404. It has been justly 

 denied (Wilde, Geschichte der Optik, th. i., s. 92-96) that the knowledge 

 derived from Alhazen, of the magnifying power of segments of spheres, 

 was actually the means of leading Bacon to construct spectacles. This 

 invention would appear to have been known as early as 1299, or to 

 belong to the Florentine Salvino degli Aimati, who was btuied in 1317 

 VA the Church of Santa Maria Maggiore at Florence. If Roger Bacon, 

 who completed his Opus Majus in 1267, speaks of instruments by means 

 of which small letters appear large, " utiles senibus habentibus oculos 

 debiles," his words prove, as do also the practically erroneous consid 

 erations which he subjoins, that he can not himself have executed that 

 which obscurely floated before his mind as possible. 



