HYPOTHESES. 



321 



§ 3. As, however, there is scarcely 

 any one of the principles of a true 

 method of philosophising 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 con- 

 demned, with some asperity, any at- 

 tempt to explain phenomena which 

 are "evidently primordial," (mean- 

 ing, apparently, no more than that 

 every peculiar phenomenon must 

 have at least one peculiar and there- 

 fore inexplicable law,) has spoken of 

 the attempt to furnish any explana- 

 tion of the colour belonging to each 

 substance, " la couleur el^mentaire 

 propre k chaque substance," as essen- 

 tially illusory. "No one," says he, 

 " in our time attempts to explain the 

 particular specific gravity of each sub- 

 stance or of each structure. Why 



tion, they differ widely ; so widely that we 

 should hiive to state totally distinct laws 

 for each. Gravity is common to all matter, 

 uud 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 

 indestructible and invariable. Cohesion is 

 special for each separate substance ; it de- 

 creases according to distance much more 

 rapidly than the inverse square, vanishing 

 entirely at very small distances. Two such 

 forces have not suflBcient kindred to be 

 generalised into one force ; the generalisa- 

 tion is only illusory ; the itatement 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 generalisation of 

 gravity itself." 



To the impassable limit of the explana- 

 tion of laws of nature, set forth in the text, 

 must therefore be added a further limita- 

 tion. 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 pro- 

 ducing them according to the same law. 

 Otherwise tlie unity of cause is a mere 

 guess, and the generalisation only a nomi- 

 nal one, which, even if admitted, would 

 not diminish the number of ultimate laws 

 ul nature, 



should it be otherwise as to the 

 specific colour, the notion of which 

 is undoubtedly no less primordial?" * 



Now, although, as he elsewhere ob- 

 serves, a colour must always remain 

 a different thing from a weight or a 

 sound, varieties of colour might never- 

 theless follow, or correspond to, given 

 varieties of weight, or sound, or some 

 other phenomenon as different as 

 these are from colour 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 inter- 

 dict against endeavouring to reduce 

 distinctions of colour 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 immediatelypreceded and caused 

 by distinguishable varieties in the 

 vibrations of elastic bodies, though a 

 sound, no doubt, is quite as different 

 as a colour is from any motion of 

 particles, vibratory or otherwise. We 

 might add, that, in the case of colours, 

 there are strong positive indications 

 that they are not ultimate properties 

 of the different kinds of substances, 

 but depend on conditions capable of 

 being superinduced upon all sub- 

 stances ; since there is no substance 

 which cannot, according to the kind 

 of light thro\vn upon it, be made to 

 assume almost any colour ; and since 

 almost every change in the mode of 

 aggregation of the particles of the 

 same substance is attended with 

 alterations in its colour, and in its opti- 

 cal properties generally. 



The really weak point in the at- 

 tempts which have been made to 

 account for colours by the vibrations 

 of a fluid, is not that the attempt itself 

 is unphilosophical, but that the exist- 

 ence of the fluid, and the fact of its 



* Court de JPkilosophie Potitive, ii. 656. 



