Page:On the connexion of the physical sciences (1834).djvu/35

the other systems of the universe. Should there be no link between them, it may be inferred, from the rotation of the sun, that the centre of gravity of the system situate within his mass describes a straight line in this invariable plane or great equator of the solar system, which, unaffected by the changes of time, will maintain its stability through endless ages. But if the fixed stars, comets, or any unknown and unseen bodies, affect our sun and planets, the nodes of this plane will slowly recede on the plane of that immense orbit which the sun may describe about some most distant centre, in a period which it transcends the powers of man to determine. There is every reason to believe that this is the case; for it is more than probable that, remote as the fixed stars are, they in some degree influence our system, and that even the invariability of this plane is relative, only appearing fixed to creatures incapable of estimating its minute and slow changes during the small extent of time and space granted to the human race. 'The development of such changes,' as M. Poinsot justly observes, 'is similar to an enormous curve, of which we see so small an arc that we imagine it to be a straight line.' If we raise our views to the whole extent of the universe, and consider the stars, together with the sun, to