2.48 Mr \ HER5CH el on the proper Motion 
Aidebaran, Procyou, Caftor, Rigel, Altair, and many more, 
to be adually in motion ; and confidering the ftiortnefs of the 
time we have had obfervations accurate enough for thepurpofe, 
we may rather wonder that we have already been able to find 
the motions of fo many, than that we have not difeovered the 
like alterations in all the reft. Betides, we are well prepared 
to find numbers of them apparently at reft, as, on account of 
their immenfe diftance, a change of place cannot be expected to 
become vifible to us till after many ages of careful attention 
and dole oblervation, though every one of them lhould have a 
motion of the fame importance with Ardurus. This confide- 
ration alone would lead us ftrongly to fufped, that there is not, 
in ftridnefs of fpeaking, one fixed ftar in the heavens ; but 
many other reafons, which I fhall prefently adduce, will ren- 
der this fo obvious, that there can hardly remain a doubt of 
the general motion of all the ftarry fyftems, and confequently 
of the folar one among the reft. 
I might begin with principles drawn from the theory of 
attradion, which evidently oppofe every idea of abfolute reft 
m any one of the ftars, when once it is known that fome of 
them are in motion for the change that muft arife by fuch 
motion, in the value of a power which ads inverfely as the 
fquares of the diftances, muft be felt in all the neighbouring 
ftars ; and if thefe be influenced by the motion of the former, 
they will again affed tliofe that are next to them, and fo on till 
all are in motion. Now as we know feveral ftars, in divers 
parts of the heavens, do adually change their place, it will 
follow, that the motion of our folar fyftem is not a mere hy- 
pothefis ; and what will give additional weight to this confide- 
ration is, that we have the greateft reafon to fuppofe moft of 
thofe very ftars, which have been obferved to move, to be 
fuch 
