Mechanics, Volume I

-se accepted, place is usually called absolute, so that it may be distinguished from relative place, of which mention will soon be made.

Corollary 1.

5. When, therefore, a body successively occupies one part after another of this immense space, it moves; but if it persists perpetually in the same seat, then it is at rest.

Corollary 2.

6. Moreover, it is common to conceive in the mind fixed boundaries of this space to which bodies are referred. And this relation is what is called position position: Latin situs, referring to the arrangement or location of an object relative to points of reference. Therefore, those bodies which maintain the same position with respect to these boundaries are said to be at rest. On the other hand, those which change their position are said to move.

Scholion 1.

7. If the terms set forth are taken in this sense, they are usually called absolute motion and absolute rest. And these are the true and genuine definitions of those terms, for they are adapted to the laws of motion which will be explained in what follows. Since, however, we can form no certain idea of that immense space and its boundaries (which were mentioned in the given definitions), we are instead accustomed to consider a finite space and corporeal limits Euler is explaining that while "absolute space" exists mathematically, humans can only measure motion relative to physical objects like the Earth or stars, from which we judge the motion and rest of bodies. Thus we are accustomed to say that a body, which re-