The eminent English scientist, Sir William Crookes, in his address as president of the Royal Society, at Bristol, England, a few years ago, said: "Were I now introducing for the first time these inquiries to the world of science, I should choose a starting point different from that of old, where we formerly began. It would be well to begin with telepathy; with the fundamental law, as I believe it to be, that _thoughts and images may be transferred from one mind to another without the agency of the recognized organs of sense_--that knowledge may enter the human mind without being communicated in any hitherto known or recognized ways. Although the inquiry has elicited important facts with reference to the mind, it has not yet reached the scientific stage of certainty which would enable it to be usefully brought before one of our sections. I will therefore confine myself to pointing out the direction in which scientific investigation can legitimately advance. If telepathy take place, we have two physical facts--the physical change in the brain of A. the suggestor, and the analogous physical change in the brain of B. the recipient of the suggestion. Between these two physical events there must exist a train of physical causes. Whenever the connecting sequence of intermediate causes begins to be revealed, the inquiry will then come within the range of one of the sections of the British Association. Such a sequence can only occur through an intervening medium. All the phenomena of the Universe are presumably in some way continuous, and it is unscientific to call in the aid of mysterious agencies when with every fresh advance in knowledge, it is shown that ether vibrations have powers and attributes abundantly equal to any demand--even the transmission of thought."