Mr. ELLIS, ON THE THEORY OF MATTER. 603 



liquid when the acid is inti-oduced into it begins to act on the luminiferous vibrations which exist 

 near it in a different manner from that in which it had previously acted. The whole change, whe- 

 ther we call it a chemical phenomenon or not, consists in the introduction of new forms of motion 

 in virtue of the action of mechanical force. 



7. From considerations of this kind it appears to follow that a complete explanation of all 

 phenomena would introduce no principles beyond those with which the science of mechanics 

 is conversant. And in truth if the conclusion drawn had been that all phenomena might, if our 

 knowledge of nature were sufficiently extensive, be reduced to cinematical considerations (using 

 the word cinematics in the large sense in which it is equivalent to the doctrine of motion), 

 I do not see how on our fundamental hypothesis we could refuse to assent to it. But the con- 

 clusion drawn by the maintainers of the all-sufficiency of a mechanical philosophy is something 

 different from this — and as I conceive the error they appear to have committed is to be sought 

 for in this discrepancy. But before entering into the discussion of this point, I will make a few 

 remarks on certain points in the history of what may be called the theory of matter. 



8. If we suppose the maxim that secondary qualities are to be explained by means of the 

 primary to have been accepted (either in that or in some equivalent form) or if not formally 

 accepted, at least unconsciously assumed, at a time when the idea of mechanical force was as yet 

 very imperfectly apprehended — the natural result of this state of things is the formation of 

 an atomic theory. For in order to individuate the constitution of any given body, we could only 

 have had recourse to the configuration or motion of its parts. Gold, to return to our previous 

 example, was said to be yellow in virtue of such and such a configuration of its parts ; since 

 except configuration there appeared to be no disposable circumstance*, if I may so speak, 

 whereby gold was in its intimate constitution to be distinguished from silver or from any thing 

 else. But this configuration must be independent of the bodys visible and external form, since 

 changes of the latter do not affect the body's sensible qualities. Hence it must be a configuration 

 of small parts, and we are thus at once led to the primitive form of the atomic theory. In this 

 the atoms possess the primary qualities of larger bodies — they are of various forms and act if the 

 expression may be used by their forms, not by being centres of attractive forces. Such was the 

 atomistic system of the school of Democritusf — a system which as we know found no little favour 

 among the scientific reformers of the seventeenth century |. As an instance of the influence it 

 exerted, I need only mention the great work of Cudworth, in which it is presented ajiart from 

 the atheistical doctrines with which it had often been connected. Cudworth goes so far as to 

 affirm that Democritus and his followers had corrupted and degraded the atomistic system which 

 was originally altogether free from any irreligious tendency and which he sought to restore 

 to its first estate. 



But as the imperfections of the atomic system became manifest, and on the other liand mecha- 

 nical conceptions came to be more developed a new form of this system arose. The atoms, 

 retaining their forms and those which are commonly called their primary qualities, were now 

 supposed to act as centres of attractive force, in other words, each atom was to the rest a cause of 

 motion. But as the ordinary " jirimary qualities" of bodies may as we have seen be analysed into 

 conceptions which involve nothing beside motion and force, this new form of the docliinc may 

 clearly be considered merely as a state of transition to that which is now known i)y the title 



• Specific (litfcrc-nccs of motion seem for more than one reason I with in tlic writin^ii of modern historians of jihilosopliy, Zcllcr's 



not to have been used in giving' an account of the differences of 

 bodies. 



t .See for a more favourable, anil I think, a juster view of the 

 philoiwphy of Democritus than that wiiich we cotmnonly meet 



l'hihso)Mi: Der Oriechen, i. § 10. 



X The physical theories of I)e« ('iirles. though not properly 

 atomistic, since he proceeded on the hypothesis of a plenum, yet 

 in many respects are akin to those of which we are speaking. 



