But we may diſtinguiſh Reſt and Motion, abſolute and relative, one from the other by their Properties, Cauſes and Effects. It is a property of Reſt, that bodies really at reſt do reſt in reſpect of one another. And therefore as it is poſſible, that in the remote regions of the fixed Stars, or perhaps far beyond them, there may be ſome body abſolutely at reſt; but impoſſible to know from the poſition of bodies to one another in our regions, whether any of theſe do keep the ſame poſition to that remote body; it follows that abſolute reſt; cannot be determined from the poſition of bodies in our regions.
It is a property of motion, that the parts, which retain given poſitions to their wholes, do partake of the motions of thoſe wholes. For all the parts of revolving bodies endeavour to recede from the axe of motion; and the impetus of bodies moving forwards, ariſes from the joint impetus of all the parts. Therefore, if ſurrounding bodies are mov'd, thoſe that are relatively at reſt within them, will partake of their motion. Upon which account, the true and abſolute motion of a body cannot be determin'd by the tranſlation of it from thoſe which only ſeem to reſt: For the external bodies ought not only to appear at reſt, but to be really at reſt. For otherwiſe, all included bodies, beſide their tranſlation from near the ſurrounding ones, partake likewiſe of their true motions; and tho' that tranſlation was not made they would not be really at reſt, but only ſeem to be ſo. For the ſurrounding bodies ſtand in the like relation to the ſurrounded, as the exterior part of a whole does to the interior, or as the ſhell does to the kernel; but, if the ſhell moves, the kernel will alſo move, as being part of the whole, without any removal
from near the ſhell.
