412 
of real objects, but 'with reference to empty space alone. But is 
this possible ? If a body were quite alone in the universe, could 
it move ? Move it in thought as you please, will it not be just the 
same as before, alone with an infinite void on all sides ? In this 
vast solitude there are no landmarks, nothing to which motion 
could be referred. But a motion which changes nothing, an 
alters no relation of distance, must be the same with absolute rest. 
I cannot conceive a motion when there is nothing to approach to, 
or from which to move further away. Newton writes on this 
subject as follows : — 
28. “ All things are placed in space as to order of situation. It is from 
their essence or nature that they are placed, and that the primary places of 
things should be movable is absurd. These then are the absolute places, 
and translations out of these are the absolute motions. But because the 
parts of space cannot be seen or distinguished by our senses, in their stead 
•we use sensible measures of them. From the positions and distances of 
things from some body, considered as immovable, we define all places, and 
with respect to such places we estimate all motions. So, instead of absolute 
places and motions we use relative ones, and that without inconvenience in 
common affairs. But in philosophical disquisitions we ought to abstract 
from our senses, and consider things in themselves. For it may be that 
there is no body really at rest, to which the places and motions of others 
may be referred. It is possible that in the remote regions of the fixed stars, 
or perhaps far beyond them, there may be some body absolutely at rest ; but 
it is impossible to know, from the position of bodies one to another in our 
regions, whether any of these do keep their positions to that remote body. 
Thus absolute rest cannot be determined from the positions of bodies in our 
regions All motions from places in motion are no other than 
parts of the entire and absolute motions. Entire and absolute motions are 
not otherwise to be determined than by immovable places. Now no other 
places are immovable but those that from infinity to infinity do always 
retain the same given positions one to another, and on this account must 
remain unmoved, and thereby consitute what I call immovable space. 
29. Thus, Newton holds it doubtful whether any body be really 
at rest, though he thinks such a body may, perhaps, exist in some 
remote part of the universe. If it exist, absolute motions will be 
those relative to this unknown body. In other words, they are 
relative still, but the relation is to a hypothetical body, of which 
we cannot know where it is to be found, or whether it really 
exists. 
We must revert, then, to another conception. Absolute 
motions are those which are referred to no real body at all, but to 
the points, assumed to be immovable, of empty space. Is this a 
true and valid conception ! Do we not really, in our thoughts, 
