All this is said merely to indicate the key to this kind of science; for the combinations in which these principles may enter, and the modifications of their manifestations under different conditions are almost innumerable; neither can this spiritual science be taught to a mind (_Manas_) unillumined by the light of the higher understanding (_Buddhi_). The practical study and application of anything requires first of all the possession of the object, and if this is true in regard to physical objects, it is no less true in regard to spiritual principles, whose nature can only be known when their presence is realised within one’s own consciousness. The higher aspects of all of these powers belong to the higher nature of man, and he who desires to know and apply these laws in the practice of medicine, must first of all seek to develop his own higher nature by freeing himself from the elements that govern his lower nature; in other words, he must enter from the animal-human into the human-divine state, to which the true physician belongs. One of such adept-physicians was _Theophrastus Paracelsus_, the great reformer of medicine of the sixteenth century, who is properly regarded as the father of modern medicine, although his successors are still far from realising the truths which he taught, and will, on the whole, perhaps not grow up to an understanding of his doctrines for centuries to come.[4] He was far in advance not only of the science of his days, but also of that of our present days; for although he may have known less than we do in regard to the phenomenal appearances of the manifestations of life on this planet, he knew a great deal more than our modern science in regard to the causes of these manifestations and in regard to the _inner_ nature of things. He was and still is ridiculed and belittled by those who were and are not capable of understanding him; but he proved the truth of his theories by performing cures which even modern medicine with all its new acquisitions cannot perform.[5] He was the first to abolish a system of unmitigated quackery, based upon mere empiricism, the remnants of which exist even to-day. He was hated and persecuted by the quacks and pretenders of those times, who did a lucrative business, thriving upon the ignorance of the public, as some are doing to-day, and the vilifications and calumnies thrown out against him by such still inspire the opinions of many in regard to his person, although we may safely believe that few of his critics have ever read his books and still fewer have understood them. Numerous biographies have been written about him and his personal habits, and it seems that the majority of his critics have been able to comprehend that when he died he left a pair of leather pantaloons to his heirs; but as to his philosophy, this is a _terra incognita_, which surpasses their understanding; neither could such a knowledge of the secret sciences be