348 INDUCTION. 



§ 3. As, liowever, there is scarcely any one of the principles of a true 

 method of philosophizing which does not require to be guarded against 

 errors on both sides, I must enter a caveat against another misapprehen- 

 sion, of a kind directly contrary to the preceding. M. Comte, among other 

 occasions on which he has condemned, with some asperity, any attempt to 

 explain phenomena which are " evidently primordial " (meaning, apparent- 

 ly, no more than that every peculiar phenomenon must have at least one 

 peculiar and therefore inexplicable law), has spoken of the attempt to fur- 

 nish any explanation of the color belonging to each substance, " la couleur 

 elementaire propre a chaque substance," as essentially illusory. "No one," 

 says he, " in our time attempts to explain the pai-ticular specific gravity of 

 each substance or of each structure. Why should it be otherwise as to 

 the specific color, the notion of which is undoubtedly no less primordial ?"* 



Now although, as he elsewhere observes, a color must always remain a 

 different thing from a weight or a sound, varieties of color might neverthe- 

 less follow, or correspond to, given varieties of weight, or sound, or some 

 other phenomenon as different as these are from color itself. It is one 

 question what a thing is, and another what it depends on ; and though to 

 ascertain the conditions of an elementary phenomenon is not to obtain any 

 new insight into the nature of the phenomenon itself, that is no reason 

 against attempting to discover the conditions. The interdict against en- 

 deavoring to reduce distinctions of color to any common principle, would 

 have held equally good against a like attempt on the subject of distinctions 

 of sound ; which nevertheless have been found to be immediately preceded 

 and caused by distinguishable varieties in the vibrations of elastic bodies ; 

 though a sound, no doubt, is quite as different as a color is from any mo- 

 tion of particles, vibratory or otherwise. We might add, that, in the case 

 of colors, there are strong positive indications that they are not ultimate 



phenomena under a common statement. The similarity of terrestrial gravity to celestial at- 

 traction enahles the two to be expressed as one phenomenon. The similarity between cap- 

 illary attraction, solution, the operation of cements, etc., leads to their being regarded not as 



a plurality, but as a unity, a single causative link, the operation of a single agency If 



it be asked whether we can merge gravity itself in some still higher law, the answer must de- 

 pend upon the facts. Are there any other forces, at present held distinct from gravity, that 

 we may hope to make fraternize with it, so as to join in constituting a higher unity ? Gravity 

 is an attractive force ; and another great attractive force is cohesion, or the force that binds 

 together the atoms of solid matter. Might we, then, join these two in a still higher unity, ex- 

 pressed under a more comprehensive law ? Certainly we might, but not to any advantage. 

 The two kinds of force agree in the one point, attraction, but they agree in no other ; indeed, 

 in the manner of the attraction, they differ widely ; so widely that we should have to state 

 totally distinct laws for each. Gravity is common to all matter, and equal in amount in equal 

 masses of matter, whatever be the kind ; it follows the law of the diffusion of space from a 

 point (the inverse square of the distance); it extends to distances unlimited; it is indestructi- 

 ble and invariable. Cohesion is special for each separate substance ; it decreases according 

 to distance much more rapidly than the inverse square, vanishing entirely at very small dis- 

 tances. Two such forces have not sufficient kindred to be generalized into one force ; the 

 generalization is only illusory ; the statement of the difference would still make two forces ; 

 while the consideration of one would not in any way simplify the phenomena of the other, as 

 happened in the generalization of gravity itself." 



To the impassable limit of the explanation of laws of nature, set forth in the text, must 

 therefore be added a further limitation. Although, when the phenomena to be explained are 

 not, in their own nature, generically distinct, the attempt to refer them to the same cause is 

 scientifically legitimate ; yet to the success of the attempt it is indispensable that the cause 

 should be shown to be capable of producing them according to the same law. Otherwise the 

 unity of cause is a mere guess, and the generalization only a nominal one, which, even if ad- 

 mitted, would not diminish the number of ultimate laws of nature. 



* Cours de Philosophic Positive, ii. , 656. 



