essential to Matter, &c. 35

XVIII* To return then; as from N b 14and 15. it appears, that this resistance to a

change

farther afierted, that this fluid is rarer or denser in thefame body, whether small or great, according as the bo-dy to which that is impelled, is itself small or great.

In the earth, as gravitating to the moon, it must be ve-ry rare; and in the earth again, as gravitating to thefun, it must be very dense: How can the fame fluid beboth dense and rare in the same body at once ? Besides,it must be asserted, that this fluid is denser in dense bo-dies, whatever their magnitude be, than in rare ones ;for these gravitate most : which seems directly contraryto reason ; since the denser any body is, the less freelyany fluid, ever so subtile, would pervade it, to give e-very particle an impulse; and contrarily, the rarer themore freely. Moreover, if there be any solidity in bo-dies at all, which it would be strange to deny, a fluidcannot pervade, I think, to the innermost particles ofthese solid parts, to give these their impulse, withoutsupposing a penetration of dimensions: acting accordingto their number, is acting according to the very solidityof bodies.

In this particular, let me reason as things appear tomyself; because possibly they may appear the same wayto others. If every particle through the whole solidityof a heavy body, received its impulse from the particlesof this fluid, it should seem that the fluid itself must beas dense as the very densest heavy body, gold for instance;or that there must be as many impinging particles in theone, as there are gravitating panicles in the other, which

D 2, receive