EIGHTEENTH CENTURY EVOLUTIONISTS. 251 



tended, nor extended matter as possessing the unity characteristic of 

 conscious thought. Maupertuis certainly can not be said to meet this 

 difficulty; but he evades it by a device which has been much employed 

 since his time by metaphysicians of opinions kindred to his. The 

 objection in question, he avows, would be a legitimate one against any 

 doctrine that actually asserted the identity of matter and consciousness, 

 reducing matter to thought, or thought to a form or function of 

 matter. But if we say that thought and extension are not things, but 

 properties — distinct but joint properties of a common subject — the 

 difficulty, he contends, disappears. This tertium quid, of which thought 

 and extension are to be defined as coexisting properties, is something 

 'of which the essence is unknown to us' ('Syst. de la Nat.,' 22). 

 Maupertuis at this point appears, on the one hand, as repeating the 

 dialectical strategy of Spinoza, a philosopher almost wholly ignored in 

 the eighteenth century; and, on the other hand, as a precursor of Mr. 

 Herbert Spencer, with his conception of the 'double aspect of an ulti- 

 mately unknowable substance. ' Maupertuis, however, was not a psycho- 

 physical parallelist; on the contrary, as I have pointed out, the 

 sentiency which he attributed to matter was regarded by him as an 

 essential factor in the explanation of physical events. 



How Maupertuis would have reconciled the apparent — even though 

 'transfigured' — realism of this doctrine of conscious matter with the 

 idealistic view of the subjectivity of the perception of space, which he 

 expresses in one of the Lettres,* it is impossible to say. It may be 

 that it never occurred to him that the two opinions were discrepant; 

 it may be that he conceived it possible to reconcile them; and it may 

 be that the idealistic view, which was published later than the other, 

 implied the abandonment of the realism of the mind-stuff theory. As 

 it is, we can only say that, as a metaphysician, Maupertuis has the 

 apparently contradictory distinction of having given utterance, during 

 the middle decade of the eighteenth century, to the favorite contentions 

 of both the realism and the idealism of the nineteenth, f 



* Lettre IV. ' Sur la maniere dont nous apergevons.' For Voltaire's com- 

 ment on this, see above, p. 9, footnote. Maupertuis expresses this idealistic 

 conclusion in these terms: ' Reflechissant done sur ce qu'il n'y a aucun rapport, 

 entre nos perceptions et les objets exterieurs, on conviendra que tous ces ob- 

 jets ne sont que de simples phenomenes: l'etendue, que nous avons prise pour 

 la base de tous ces objets, pour ce qu'en concerne l'essence, l'etendue elle-meme 

 ne sera rien de plus qu'un phenomene.' 



t Historians of philosophy have unduly neglected both aspects of Maupertuis 

 as a metaphysician. Lange merely mentions his doctrine of ' empfindende 

 Atome ' in a sentence (' Gesch. d. Materialismus,' I., 259) ; Erdmann, who devotes 

 a page to Maupertuis, says nothing about his metaphvsics at all ( ' Historv of 

 Philosophy,' II., 293, 4). 



{To be continued.) 



