130 COSMIC PHILOSOPHY. [pt. i. 



two rival theories of light. According to the theory of 

 Newton, a ray of light is a linear series of material cor- 

 puscles, darted from the luminous object. According to the 

 theory of Huyghens, a ray of light is a system of molecular 

 undulations which move outward in ever-increasing con- 

 centric shells whose normals are radial, and which are set 

 in motion by undulations among the molecules of the lumi- 

 nous object. At the beginning of the present century the 

 corpuscular theory was submitted to a set of crucial investiga- 

 tions which overthrew it; and more recently the undulatory 

 theory has been submitted to a course of crucial investigation 

 which has finally established it. Both these theories were 

 scientific in conception, and previous to the researches of 

 Young and Fresnel a scientific philosopher might have con- 

 sistently espoused either. Such are the controversies of 

 science, which sooner or later have always led, and will 

 always lead, to agreement and to knowledge. Far different 

 is it with the disputes of metaphysics, which — conducted 

 upon the subjective method, and dealing with unverifiable 

 hypotheses — have never led, and can never lead, to anything 

 but an endless renewal of dispute, in scecula sceculorum. 



In this condemnation of the subjective method, the Cosmic 

 Philosophy here expounded is entirely in harmony with the 

 Positive Philosophy, as set forth in Comte's first great work, 

 and as held by M. Littre" and Mr. Mill. Indeed there is 

 probably nothing in the present chapter which might not be 

 cited by the Positivist in confirmation of his opinions as to 

 the limits of philosophical inquiry. The Positive Philosophy 

 is based upon the assertion of the relativity of all knowledge ; 

 and, however fatally inadequate may have been its psycholo- 

 gical interpretation of that doctrine, there is no ground for 

 accusing it — as represented by Mr. Mill and M. Littre — of 

 inconsistency in its adherence to the scientific method for 

 which the doctrine of relativity supplies the justification. 

 Since Bacon's time there have been few thinkers who have 



