If misunderstandings are not to arise at the outset, two things must be borne in mind in connection with this account of a second principle of human nature. The word “etheric” is used here in a different sense from that of modern physics, which designates as “ether” the medium by which light is transmitted. In occult science the use of the word is limited to the sense given above. It denotes that which is accessible to higher sight, and can be known to physical observation only by its effects, that is, by its power of giving a definite form or shape to the mineral materials and forces present in the physical body. Again, the use of the word “body” must not be misunderstood. It is necessary to use the words of every day language in describing things on a higher plane of existence, and these terms, when applied to sense-observation, express only what is physical. The etheric body has, of course, nothing of a bodily nature in the physical sense, however ethereal we might imagine such a body to be. As soon as the occultist mentions this etheric or vital body, he reaches the point at which he is bound to encounter the opposition of many contemporary opinions. The development of the human mind has been such that the mention of such a principle of human nature is necessarily looked upon as unscientific. The materialistic way of thinking has arrived at the conclusion that there is nothing to be seen in a living body but a combination of physical substances and forces such as are also found in the so-called inanimate body of the mineral, the only difference being that they are more complicated in the living than in the lifeless body. Yet it is not very long since other views were held, even by official science. It is evident to any one who studies the works of many earnest men of science, produced during the first half of the nineteenth century, that at that time many a genuine investigator of nature was conscious of some factor acting within the living body other than in the lifeless mineral. It was termed “vital force.” It is true this vital force is not represented as being what has been above characterized as the vital body, but underlying the conception was a dim idea of the existence of such a body. Vital force was generally regarded as something which in a living body was united with physical matter and forces in the same way that the force of a magnet unites itself with iron. Then came the time when vital force was banished from the domain of science. Mere physical and chemical causes were accounted all sufficient.