_Mobility_: That property whereby Substance responds to imparted Motion. We shall notice this property in our consideration of Motion. In addition to the Motion of the Mass, and the movements of Molecules and Atoms in response to its Attraction, there is another form of Motion constantly going on, without reference to the Attraction or impressed Motion of the Mass. The Molecules of all bodies are always in a state of rapid Motion, called Vibration. In solids this vibration is short, being restrained by the close cohesive position of the Molecules. But in Liquids, the Molecules being further separated, the vibration is far more rapid, and they move around and slide over each other with comparatively little resistance. In gases and vapors the Molecules have a splendid field for Motion, and consequently vibrate in wide fields and orbits, and dash around with the greatest velocity. The Atoms also are believed to vibrate rapidly, in accordance with their own laws of vibration. And the Corpuscles are believed to far excel the last two mentioned particles in intensity, rapidity and complexity of their vibrations, as we shall see a little later on in the book. All Substance is in constant Motion and Vibration. There is no Rest in Substance. _Inertia_: That property whereby Substance may not move unless in response to imparted Motion; nor terminate its Motion, when it is once imparted, except in response to some other manifestation of impressed Force. Science holds that this "impressed Force" or "imparted Motion" must come from without, but the writer holds that Force may also be "expressed" from "within," as may be seen by reference to subsequent chapters of this book. _Attraction_: That property whereby particles or bodies of Substance (1) draw other particles or bodies toward themselves; or (2) move toward other particles or bodies; or (3) are mutually drawn together. This property manifests in four forms, generally referred to as separate and distinct from each other, but which the writer believes to be but forms of the same Attractive Power, and which he believes to be a Mental Process, at the last analysis (a revolutionary claim, which will be supported by argument in later chapters of the book). These three forms of Attraction are known as (1) Gravitation; (2) Cohesion; (3) Adhesion; and (4) Chemical Affinity, or Chemism. We are invited to consider them briefly, at this point, further investigation being reserved for our chapters on Motion, and Dynamic Thought. _Gravitation_: This term is usually applied to the attraction between Masses of Substance, such as the Sun, the Earth, and Masses of Substance on or about the Earth's surface. However, Newton, who discovered the facts of Gravitation, states the Law, as: "_Every particle of matter in the Universe, attracts every other particle_," _etc._