Absolute Space

People get their commonsense notions of time, space, place, and motion from their everyday interaction with the world. For instance, they perceive a train as moving relative to them. Newton, in fact, called common-sense notions "relative" or "apparent" as opposed to the "absolute" or "mathematical" notions, which he held to be ultimately true. In Newton's view, there is an absolute space which is immovable and all things, ultimately, move relative to absolute space.

Aristotle believed that the earth was immovable, and provided the origin for the framework of fixed, absolute space. According to Newton, our senses are tricked into believing that the earth is motionless, and that we do not know the origin of absolute space. Although the earth moves around the sun, he did not believe that the sun was a caught like a fly in the flypaper of absolute space.

Absolute space, according to Newton, was not dependent on anything in the observable universe for its absoluteness, and never changed or moved. Any thought of it being warped by massive objects, or "expanding" was anathema. Such ideas would have to wait for Einstein's theory of relativity.

Relative spaces, according to Newton, were the only ones we could comprehend. These are spaces defined relative to celestial objects. For instance, you can define one relative space as centred on the sun, which is then assumed to be immobile. But, according to Newton, this relative space, and the sun, move in absolute space.

He believed that a distance measured in absolute space would be the same in a relative space. It would take Einstein's Special Theory of Relativity to show that these measurements would not be the same.

Reference: Scholium to the definitions in Philosophiae Naturalis Principia Mathematica, Bk. 1 (1689)