No doctrine taught by Joseph Smith is better understood by his followers than that matter in its elementary condition is eternal, and that it can neither be increased nor diminished. As early as May, 1833, the Prophet declared that "the elements are eternal,"[A] and in a sermon delivered in April, 1844, he said "Element had an existence from the time God had. The pure principles of element are principles which can never be destroyed; they may be organized and reorganized, but not destroyed. They had no beginning, and can have no end."[B] [Footnote A: Doctrine and Covenants, 93:33.] [Footnote B: The Contributor, Vol. 4, p. 257.] It is thus evident that from the beginning of his work, Joseph Smith was in perfect harmony with the fundamental doctrine of science; and far in advance of the religious sects of the world, which are, even at this time, slowly accepting the doctrine of the persistence of matter in a spiritual as well as in a material sense. Mormonism has frequently been charged with accepting the doctrine of materialism. In one sense, the followers of Joseph Smith plead yes to this charge. In Mormon theology there is no place for immateralism; i.e. for a God, spirits and angels that are not material. Spirit is only a refined form of matter. It is beyond the mind of man to conceive of an immaterial thing. On the other hand, Joseph Smith did not teach that the kind of tangible matter, which impresses our mortal senses, is the kind of matter which is associated with heavenly beings. The distinction between the matter known to man and the spirit matter is very great; but no greater than is the difference between the matter of the known elements and that of the universal ether which forms one of the accepted dogmas of science. Science knows phenomena only as they are associated with matter; Mormonism does the same. Chapter III. THE INDESTRUCTIBILITY OF ENERGY. [Sidenote: All forms of energy may be converted into each other. Energy can not be destroyed.] It is only when matter is in motion, or in the possession of energy, that it is able to impress our senses. The law of the indestructibility and convertibility of energy, is of equal fundamental value with that of the indestructibility of matter. A great variety of forces exist in nature, as, for instance, gravitation, electricity, chemical affinity, heat and light. These forces may all be made to do work. Energy, in fact, may be defined as the power of doing work. In early days these forces were supposed to be distinct and not convertible, one into the other, just as gold and silver, with our present knowledge, are distinct and not convertible into other elements.