That the attractive virtue of the Sun is propagated on all ſides to prodigious diſtances, and is diffuſed to every part of the wide ſpace that ſurrounds it, is moſt evidently ſhewn by the motion of the Comets; which coming from places immenſely diſtant from the Sun, approach very near to it; and ſometimes ſo near, that in their perihelia they almoſt touch its body. The theory of theſe bodies was altogether unknown to aſtronomers, till in our own times our excellent author moſt happily diſcovered it, and demonſtrated the truth of it by moſt certain obſervations. So that it is now apparent that the Comets move in conic ſections having their foci in the Sun's centre, and by radii drawn to the Sun deſcribe areas proportional to the times. But from theſe phænomena it is manifeſt, and mathematically demonſtrated, that thoſe forces, by which the Comets are retained in their orbits, reſpect the Sun, and are reciprocally proportional to the ſquares of the diſtances from its centre. Therefore the Comets gravitate towards the Sun; and therefore the attractive force of the Sun not only acts on the bodies of the Planets, placed at given diſtances and very nearly in the ſame plane, but reaches alſo to the Comets in the moſt different parts of the heavens, and at the moſt different diſtances. This therefore is the nature of gravitating bodies, to propagate their force at all diſtances to all other gravitating bodies. But from thence it follows that all the Planets and Comets attract each other mutually, and gravitate mutually towards each other; which is alſo confirmed by the perturbation of Jupiter and Saturn, obſerved by aſtronomers, which is cauſed by the mutual
actions of theſe two Planets upon each other;
