Page:The Mathematical Principles of Natural Philosophy - 1729 - Volume 1.djvu/53

Book I. at any time I happen to peak of centres as attracting, or as endued with attractive powers.

Hitherto I have laid down the definitions of uch words as are les known, and explained the ene in which I would have them to be undertood in the following discoure. I do not define Time, Space, Place, and Motion, as being well known to all. Only I must oberve, that the common people conceive thoe quantities under no other notions but from the relation they bear to enible objects. And thence arie certain prejudices, for the removing of which it will be convenient to ditinguih them into Abolute and Relative, True and Apparent, Mathematical and Common.

I. Absolute, True, and Mathematical Time, of it elf, and from its own nature, flows equably without relation to anything external, and by another name is called Duration: Relative, Apparent, and Common Time, is ome enible and external (whether accurate or unequable) meaure of Duration by the means of motion, which is commonly ued intead of True time; such as an Hour, a Day, a Month, a Year.

II Abolute Space, in its own nature, without relation to anything external, remains always imilar and immovable. Relative Space is ome movable dimenion or meaure of the absolute paces; which our enes determine, by its poition to bodies; and which is vulgarly taken for immovable pace; Such is the dimenion of a ubterraneous, an aerial, or celetial pace, determined by its poition in repect of the Earth. Abolute and Relative pace are the ame in figure and magnitude; but they do not remain always numerically the ame. For if the Earth, for intance, moves; Rh