134 t $ 3e consequences of the

course to the general principle above, whendoubts arise, viz. ‘That resisting matter cannotmove itself, nor unrejisting matter any thingelse. This will set us right j for the wholetrain of reasoning will follow of course.

XVI. From the last two paragraphs wemay fee that we torment ourselves in vainto find out the mechanical cause of the cir-culation of the blood, if by a mechanicalcause we understand certain powers plantedin matter performing this motion, ’withoutthe intervention or efficiency of any cause int'material-, so that matter with these powersplanted in it, of itself continues this motiononce begun. This is to endeavour to findout a thing which is not to be found out, be-cause it is not. We saw in N° 6. of this,the impossibility of one particle’s being car-ried round in a simple circular motion, with-out the constant agency of an immaterialpower; but if We apply this to the presentcase of a circulating fluid, ; where there is 3congeries of particles to be carried round, andconsider, besides. their constant change ofdirection, the diminution of any impulse im-pressed, from the action of these particle 3

among