Thus if the Aether were required to be elastic, then elasticity was postulated for it; if more elastic, then greater elasticity was added. If density were demanded, then density was postulated, and if less or more density, less or more density was given to it. That method of speculation may be satisfactory up to a certain point, but no one will admit that such a method is wholly philosophical. It will be a far better method to adopt, if, in dealing with the universal Aether, we can make it conform to certain recognized laws and principles, and from the application of those well-known laws, be able to infer the exact constitution of this space-filling Aether medium. Now the question arises, if Aether is gravitative, what effect has the Gravitation of any body, be it an atom, or a meteor or planet, sun or star, upon the Aether in which it moves, and which surrounds it? That we may have some light thrown upon the matter, I would like now to take the reader to Newton's _Optics_, in order that he may give us his opinion as to this property of density of the Aether. In his nineteenth query Newton (_Optics_) asks this question-- "Is not this medium much rarer within the dense bodies of the sun, stars, planets and comets than in the empty spaces between them, and in passing from them to great distances, doth it not grow denser and denser perpetually, and thereby cause the gravity of those great bodies towards one another, and of their part towards the bodies, every body endeavouring to go from the denser parts of the medium towards the rarer?" Here then we have given to us an indication of what is the possible state of things in relation to the gravitation of the Aether, and all bodies in solar and stellar space. The only mistake that Newton made, was in inverting the right order of comparatively dense and rarer parts of the aetherial medium, by putting the rarer parts of the medium near to the bodies, and supposing the denser parts to be farther away in space.