Page:The Mathematical Principles of Natural Philosophy - 1729 - Volume 1.djvu/35

Rh caues, omewhat differing from each other, the ame effect may arie; but the true caue will be that, from which it truly and actually does arie; the others have no place in true philoophy. The ame motion of the hour-hand in a clock may be occaioned either by a weight hung, or a pring hut up within. But if a certain clock hould be really moved with a weight; we hould laugh at a man that would uppoe it moved by a pring, and from that principle, uddenly taken up without farther examination, hould go about to explain the motion of the index; for certainly the way he ought to have taken hould have been, actually to look into the inward parts of the machine, that he might, find the true principle of the propoed motion. The like judgment ought to be made of thoe philoophers, who will have the heavens to be filled with a mot ubtile matter, which is perpetually carried round in vortices. For if they could explain the phænomena ever o accurately by their hypothees, we could not yet ay that they have dicovered true philoophy and the true caues of the celetial motions, unles they cou'd either demontrate that thoe caues do actually exit, or at leat, that no others do exit. Therefore if it be made clear that the attraction of all bodies is a property actually exitung in rerum natura; and if it be alo hewn how the motions of the celetial bodies may be olved by that property; it would be very impertinent for any one to object, that their motions ought to be accounted for by vortices; even though we hould never o much allow uch an explication of thoe motions to be poible. But we allow no uch thing; for the phænomen can by no means be accounted for by Rh