2. AT the end of his treatise of optics he has proposed some thoughts concerning other parts of nature, which he had not distinctly searched into. He begins with some farther reflections concerning light, which he had not fully examined. In particular he declares his sentiments at large concerning the power, whereby bodies and light act on each other. In some parts of his book he had given short hints at his opinion concerning this[338], but here he expressly declares his conjecture, which we have already mentioned[339], that this power is lodged in a very subtle spirit of a great elastic force diffused thro’ the universe, producing not only this, but many other natural operations. He thinks it not impossible, that the power of gravity itself should be owing to it. On this occasion he enumerates many natural appearances, the chief of which are produced by chymical experiments. From numerous observations of this kind he makes no doubt, that the smallest parts of matter, when near contact, act strongly on each other, sometimes being mutually attracted, at other times repelled.
3. THE attractive power is more manifest than the other, for the parts of all bodies adhere by this principle. And the name of attraction, which our author has given to it, has been very freely made use of by many writers, and as much objected to by others. He has often complained to me of having been misunderstood in this matter. What he lays upon this head was not intended by him as a philosophical explanation of any appearances, but only to point out a power in nature not hitherto distinctly observed, the cause of which, and the manner of its acting, he thought was worthy of a diligent enquiry. To acquiesce in the explanation of any appearance by asserting it to be a general power of attraction, is not to improve our knowledge in philosophy, but rather to put a stop to our farther search.
[1] Philosoph. Nat. princ. math. L. iii. introduct.
[5] Aph. 30. Errores radicales & in prima digestione mentis ab excellentia functionum & remediorum sequentium non curantur.
[12] De Cartes Princ. Phil. Part. 3. §. 52.
[21] Locke, On human understanding, B. iii.
[37] See Book II. Ch. 3. § 3, 4. of this treatise.