18o Sir I s a a c N e w t o n’s Book II.

and to be attracted by a power, which every where shouldact with degrees of strength reciprocally in the duplicateproportion of the distances; then the periods of the planetsmust observe the fame relation to their distances, as astrono-mers find them to do. But here it must not be supposed, thatthe observations of astronomers absolutely agree without anythe least difference ; and the present correction will not causea deviation from any one astronomer’s observations, so muchas they differ from one another. For in Jupiter, where thiscorrection is greatest, it hardly amounts to die 3000 th partof the whole axis.

11. Upon this head I think it not improper to mentiona reflection made by our excellent author upon these small in-equalities in the planets motions; which contains under it avery strong philosophical argument against the eternity of theworld. It is this, that these inequalities must continually in-crease by stow degrees, till they render at length the presentframe of nature unfit for the purposes, it now serves a . Anda more convincing proof cannot be desired against the pre-sent constitution’s having existed from eternity than this,that a certain period of years will bring it to an end. I amaware this thought of our author has been represented evenas impious, and as no lest than casting a reflection uponthe wisdom of the author of nature, for framing a perish-able work. But I think so bold an assertion ought to havebeen made with singular caution. For is this remarkupon the increasing irregularities of the heavenly motions

* Newt. Optics, pag. 378,

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