greateſt it produc'd no endeavour to recede from the axe: the water ſhew'd no tendency to the circumference, nor any aſcent towards the ſides of the veſſel, but remain'd of a plain ſurface, and therefore its True circular motion had not yet begun. But afterwards, when the relative motion of the water had decreas'd the aſcent thereof towards the ſides of the veſſel, prov'd its endeavour to recede from the axe; and this endeavour ſhew'd the real circular motion of the water perpetually increaſing, till it had acquir'd its greateſt quantity, when the water reſted relatively in the veſſel. And therefore this endeavour does not depend upon any tranſlation of the water in reſpect of the ambient bodies, nor can true circular motion be defin'd by ſuch tranſlations. There is only one real circular motion of any one revolving body, correſponding to only one power of endeavouring to recede from its axe of motion, as its proper and adequate effect: but relative motions in one and the ſame body are innumerable, according to the various relations it bears to external bodies, and like other relations, are altogether deſtitute of any real effect, any otherwiſe than they may perhaps participate of that one only true motion. And therefore in their ſyſtem who ſuppoſe that our heavens, revolving below the ſphere of the fixt Stars, carry the Planets along with them; the ſeveral parts of thoſe heavens, and the Planets, which are indeed relatively at reſt in their heavens, do yet really move. For they change their poſition one to another (which never happens to bodies truly at reſt) and being carried together with their heavens, participate of their motions, and as parts of revolving wholes, endeavour to recede from the axe of their motions.
Wherefore relative quantities, are not the quantities
themſelves, whoſe names they bear, but thoſe ſenſible
