186. If the truths of mathematics seemed to Berkeley explicable on this supposition, those of the physical sciences were not likely to seem less so. As long as the relations with which these sciences deal are relations between ‘sensible objects,’ he does not notice that they _are_ relations, and therefore not feelings or felt, at all. He treats felt things as if the same as feelings, and ignores the relations altogether. Thus a so-called ‘sensible’ motion causes him no difficulty. He would be content to say that it was a succession of ideas, not perceiving that motion implies a relation between spaces or moments as successively occupied by something that remains one with itself--a relation which a mere sequence of feelings could neither constitute nor of itself suggest. It is only about a motion which does not profess to be ‘seen,’ such as the motion of the earth, that any question is raised--a question easily disposed of by the consideration that in a different position we should see it. ‘The question whether the earth moves or not amounts in reality to no more than this, to wit, whether we have reason to conclude from what hath been observed by astronomers, that if we were placed in such and such circumstances, and such or such a position and distance both from the earth and sun, we should perceive the former to move among the choir of the planets, and appearing in all respects like one of them: and this by the established rules of nature, which we have no reason to mistrust, is reasonably collected from the phenomena’ (‘Principles of Human Knowledge,’ sec. 58). [1] [1] Cf. ‘Dialogues,’ page 147, in Prof. Fraser’s edition. If they imply permanent relations, his theory properly excludes them. He supposes a divine decree that one feeling shall follow another.