The first rule dealt with the general simplicity of Nature's mode of working, and therefore the general simplicity which must govern our hypotheses in perfecting any theory as to the cause of all phenomena, gravitational or otherwise. The second rule showed that the only sound basis from whence we could derive all our data upon which to speculate and reason, lay in our experience of all natural phenomena. Whatever else we might do, or not do, it was absolutely necessary, if we wished to be perfectly philosophical in our conclusions, that we should not traverse the direct results of observations and experiments. The third rule laid down was the obvious axiom, that the theory so perfected by logical reasoning must satisfactorily account for and explain all the phenomena sought to be explained. Now I wish to submit the whole theory as propounded in this work in its completion and in its entirety to the reader, and to ask him if the Rules of Philosophy have not been adhered to throughout the whole work? Can any theory be more simple than the one submitted in this work, by which we have endeavoured to account for all, and even more, than was premised in the opening chapters? The very simplicity of the fundamental hypothesis that Aether is matter, in all its properties and qualities, has been the chief obstacle to the retardation of its earlier discovery. Any proposition more simple, more easy of comprehension, is, to my mind, difficult of conception. Why, children in our homes and schools may be taught the truth, and grasp it in its concrete form, and that is the highest test of the simplicity of any hypothesis. Thus the first Rule of Philosophy is satisfied and fulfilled in the initial hypothesis, and I venture to affirm that the same simplicity has characterized the development of the theory throughout its entire progress. Step by step, simple facts and simple truths which are known to any ordinary student have been shown to have a wider and more universal application than even the writer dreamed of, when he started out on his voyage of discovery in philosophical research. When we consider the second Rule of Philosophy in its application to our theory, we find that experience, as revealed by observation and experiment, is fulfilled to the minutest detail. The simple hypothesis that Aether is matter, fulfils to the very fullest extent all requirements demanded by the experience of all the scientists and experimentalists that the world has ever known. To assert that Aether is not matter is to assert a proposition contrary to all the accumulated experience of the past generations. Therefore, if Aether is matter, then its fundamental qualities must be those which belong to and are associated with all matter, those qualities being atomicity, gravity, density, elasticity, inertia, and compressibility.