If I am good for anything, it is for a certain faculty of lucid condensation, and I have thought that I might apply this to some of the less-known branches of modern science, such as the new chemistry and physiology, as well as, in my first work, to the more familiar subjects of astronomy and geology; while at the same time I might extend it to some of the more obvious problems of religion, morals, metaphysics, and practical life, which force themselves, more and more every day, on the attention of intelligent thinkers. As in the former work the scientific speculations were linked together by the leading idea of the universality of law, so, in this, unity is given to them by the all-pervading principle of polarity, which manifests itself everywhere as the fundamental condition of the material and spiritual universe. For the scientific portion of the work I am indebted to the most approved authorities, such as Darwin, Huxley, Haeckel, and Professor Cooke’s volume on the New Chemistry in the International Scientific Series. For the religious and philosophical speculations I am myself responsible; for, although I have derived the greatest possible pleasure and profit from Herbert Spencer’s writings, I had arrived at my principal conclusions independently before I had read any of his works. I can only hope that I may have succeeded in presenting a good many abstruse questions in a popular form, intelligible to the average mind of ordinary readers, and calculated, if it teaches nothing else, to teach them a practical philosophy which inculcates tolerance and charity, and assists them in finding Sermons in stones and good in everything. CONTENTS. PAGE CHAPTER I. INTRODUCTORY. Experiment with magnet—Principle of polarity—Applies universally—Analogies in spiritual world—Zoroastrian religion—Changes in modern environment—Require corresponding changes in religions and philosophies 1 CHAPTER II. POLARITY IN MATTER—MOLECULES AND ATOMS. Matter consists of molecules—Nature of molecules—Laws of their action in gases—Law of Avogadro—Molecules composed of atoms—Proved by composition of water—Combinations of atoms—Elementary substances—Qualities of matter depend on atoms—Dimensions and velocities of molecules and atoms—These are ascertained _facts_, not theories 9 CHAPTER III. ETHER. Ether proved by light—Light-waves—Elasticity of ether—Its universal diffusion—Influences molecules and atoms—Is influenced by them—Successive orders of the infinitely small—Illustrated by the differential and integral calculus—Explanation of this calculus—Theory of vortex rings 21