psychical, and that in some persons the latter is as much in evidence as the former. We have to enquire then what relations the crystal or other medium has to the development and exercise of the clairvoyant faculty. We know comparatively little about atomic structure in relation to nervous organism. The atomicity of certain chemical bodies does not inform us as to why one should be a deadly poison and another perfectly innocuous. We regard different bodies as congeries of atoms, but it is a singular fact that of two bodies containing exactly the same elements in the same proportions the one is poisonous and the other harmless. The only difference between them is the atomic arrangement. The atomic theory refers all bodies to one homogeneous basic substance, which has been termed protyle (proto-hyle), from which, by means of a process loosely defined as differentiation, all the elements are derived. These elements are the result of atomic arrangement. The atoms have various vibrations, the extent of which is called the mean free path of vibration; greatest in hydrogen and least in the densest element. All matter is indestructible, but at the same time convertible, and these facts, together with the absolute association of matter and force, lead to the conclusion that every change of matter implies a change of force. Matter, therefore, is ever living and active, and there is no such thing as dead matter anywhere. The hylo-idealists have therefore regarded all matter as but the ultimate expression of spirit, and primarily of a spiritual origin.