parts of the body be equal to the impreſſion of the fore parts of the body on the fluid, that is unleſs the relative velocity with which the fluid puſhes the body behind is equal to the velocity with which the body puſhes the fluid; that is, unleſs the abſolute velocity of the recurring fluid be twice as great as the abſolute velocity with which the fluid is driven forwards by the body; which is impoſſible. Therefore the reſiſtance of fluids ariſing from their vis inertia can by no means be taken away. So that we muſt conclude that the celeſtial fluid has no vis inertia, becauſe it has no reſiſting force; that it has no force to communicate motion with, becauſe it has no vis inertia; that it has no force to produce any change in one or more bodies, becauſe it has no force wherewith to communicate motion; that it has no manner of efficacy, becauſe it has no faculty wherewith to produce any change of any kind. Therefore certainly this hypotheſis may be juſtly called ridiculous, and unworthy a philoſopher; ſince it is altogether without foundation, and does not in the leaſt ſerve to explain the nature of things. Thoſe who would have the Heavens filled with a fluid matter, but ſuppoſe it void of any vis inertia; do indeed in words deny a vacuum, but allow it in fact. For, ſince a fluid matter of that kind can no ways be diſtinguiſhed from empty ſpace; the diſpute is now about the names, and not the natures of things. If any are ſo fond of matter, that they will by no means admit of a ſpace void of body; let us conſider, where they muſt come at laſt.
For either they will ſay, that this conſtitution of a world every where full, was made ſo by the
will of God to this end, that the operations of
