PHYSICAL SCIENCE IN THE MIDDLE AGES. 515 



" Since this work is thus so important in the history of Inductive 

 Philosophy, I shall give, in a Note, a view 3 of its divisions and con- 

 tents. But I must now endeavor to point out more especially the way 

 in which the various principles, which the reform of scientific method 

 involved, are here brought into view. 



" One of the first points to be noticed for this purpose, is the resist- 

 ance to authority ; and at the stage of philosophical history with which 

 we here have to do, this means resistance to the authority of Aristotle, as 

 adopted and interpreted by the Doctors of the Schools. Bacon's work 4 

 is divided into Six Parts ; and of these Parts, the First is, Of the four 

 universal Causes of all Human Ignorance. The causes thus enumer- 

 ated 5 are : the force of unworthy authority ; traditionary habit ; 

 the imperfection of the undisciplined senses ; and the disposition to 

 conceal our ignorance and to make an ostentatious show of our knowl- 

 edge. These influences involve every man, occupy every condition. 

 They prevent our obtaining the most useful and large and fair doc- 

 trines of wisdom, the secrets of all sciences and arts. He then proceeds 

 to argue, from the testimony of philosophers themselves, that the au- 

 thority of antiquity, and especially of Aristotle, is not infallible. ' We 

 find 6 their books full of doubts, obscurities, and perplexities. They 



3 Contents of Roger Bacon's Opus Majus : 

 Part I. On the four causes of human ignorance: Authority, Custom, Popular 



Opinion, and the Pride of supposed Knowledge. 

 Part II. On the source of perfect wisdom in the Sacred Scripture. 

 Part III. On the Usefulness of Grammar. 

 Part IV. On the Usefulness of Mathematics. 



(1.) The Necessity of Mathematics in Human Things (published sepa- 

 rately as the Specula, Mathematica) . 



(2.) The Necessity of Mathematics in Divine Things. 1. This study 



has occupied holy men : 2. Geography : 8. Chronology : 4. 



Cycles ; the Golden Number, &c. : 5. Natural Phenomena, as the 



Kainbow: 6. Arithmetic: 7. Music. 



(3.) The Necessity of Mathematics in Ecclesiastical Things. 1. The 



Certification of Faith : 2. The Correction of the Calendar. 

 (4.) The Necessity of Mathematics in the State. 1. Of Climates : 2. 



Hydrography: 3. Geography: 4. Astrology. 

 Part V. On Perspective (published separately as Perspective,). 

 (1.) The organs of vision. 

 (2.) Vision in straight lines. 

 (3.) Vision reflected and refracted. 

 (4.) De multiplicatione specierum (on the propagation of the impressions 



of light, heat, &c.) 

 Fart VI. On Experimental Science. 



Op. 3faj. p. 1. 5 Ib. p. 2. Ib. p. 10. 



