LAW OF CAUSATION. 403 



being the only conceivable origin of material phenomena, is itself inconceivable ; 

 the attempt to rebut this argument by asserting that the mode, not the fact, of 

 the action of mind on matter was represented as inconceivable, is an abuse of 

 the privilege of writing confidently about authors without reading them : for 

 any knowledge whatever of Leibnitz would have taught those who thus speak 

 of him, that the inconceivability of the mode, and the impossibility of the thing, 

 were in his mind convertible expressions. What was his famous Principle of 

 the Sufficient Eeason, the very corner stone of his philosophy, from which the 

 Preestablished Harmony, the doctrine of Monads, and all the opinions most 

 characteristic of Leibnitz, were corollaries ? It was, that nothing exists, the 

 existence of which is not capable of being proved and explained a priori ; the 

 proof and explanation in the case of contingent facts being derived from the 

 nature of their causes ; which could not be the causes unless there was some- 

 thing in their nature showing them to be capable of producing those particular 

 effects. And this "something" which accounts for the production of physical 

 effects, he was able to find in many physical causes, but could not find it in any 

 finite minds, which therefore he unhesitatingly asserted to be incapable of pro- 

 ducing any physical effects whatever. "On ne saurait concevoir," he says, 

 "une action re*ciproque de la matiere et de 1'intelligence 1'une sur 1'autre," and 

 there is therefore (he contends) no choice but between the Occasional Causes 

 of the Cartesians, and his own Preestablished Harmony, according to which 

 there is no more connexion between our volitions and our muscular actions 

 than there is between two clocks which are wound up to strike at the same 

 instant. But he felt no similar difficulty as to physical causes : and throughout 

 his speculations, as in the passage I have already cited respecting gravitation, 

 he distinctly refuses to consider as part of the order of nature any fact which is 

 not explicable from the nature of its physical cause. 



With regard to the Cartesians (not Descartes ; 1 did not make that mistake, 

 though the reviewer of Dr. Tulloch's Essay attributes it to me) I take a passage 

 almost at random from Malebranche, who is the best known of the Cartesians, 

 and, though not the inventor of the system of Occasional Causes, is its principal 

 expositor. In Part 2, chap. 3, of his Sixth Book, having first said that matter 

 cannot have the power of moving itself, he proceeds to argue that neither can 

 mind have the power of moving it. " Quand on examine I'ide'e que Ton a de 

 tous les esprits finis, on ne voit point de liaison ne*cessaire entre leur volonte* et 

 le mouvement de quelque corps que ce soit, on voit au contraire qu'il n'y en a 

 point, et qu'il n'y en peut avoir ;" (there is nothing in the idea of finite mind 

 which can account for its causing the motion of a body ;) " on doit aussi con- 

 clure, si on veut raisonner selon ses lumieres, qu'il n'y a aucun esprit crdd qui 

 puisse remuer quelque corps que ce soit comme cause veritable ou principale, de 

 me'me que 1'on a dit qu'aucun corps ne se pouvait remuer soi-mSme :" thus the 

 idea of Mind is according to him as incompatible as the idea of Matter with the 

 exercise of active force. But when, he continues, we consider not a created but 

 a Divine Mind, the case is altered ; for the idea of a Divine Mind includes omni- 

 potence ; and the idea of omnipotence does contain the idea of being able to 

 move bodies. Thus it is the nature of omnipotence which renders the motion 

 of bodies even by the divine mind credible or conceivable, while, so far as 

 depended on the mere nature of mind, it would have been inconceivable and 



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