But above and beyond all the foregoing general considerations the "empirical facts" and the "circumstantial evidence," if we know personally one who claims to have had the specific instruction, the personal experience, and to have made the scientific demonstration referred to and outlined in the problem, our opportunity for instruction, and for the application of tests for validity and reasonableness as to the whole problem, is exceedingly valuable. This personal acquaintance may become the nearest possible criterion, short of our own personal experience, as to demonstration. In previous chapters this phase of the subject has, perhaps, been sufficiently dwelt upon. The Master may say, "I know; I have had the personal experience; I have demonstrated." The student may at last say, "I believe; I am convinced; I am satisfied." All through the foregoing pages the effort has continually been made to preserve clearly this distinction. In tracing analogies through the history of the past, the conditions, premonitory, present, and subsequent to great world-movements have often been referred to. Nothing is more common or more patent than the oft-repeated saying, "This is the age of science." Any great movement that undertakes at the present day to deal with the deeper problems of individual and social life, must fit in and conform to the "spirit of the present age." To that platform it must appeal; in that language it must be addressed, and by such judgment and criterion must it stand or fall. All these tests and criteria have been fully met by the School of Natural Science, and they are clearly outlined and set forth in the "Great Work," addressed to "the Progressive Intelligence of the Age." There need be no misconception or misinterpretation at this point. It is true that superficial thinkers and readers, enthusiasts and emotionalists, are likely to infer that the science of the soul can now be had "for a consideration" and in "a dozen easy lessons." All such are doomed to disappointment. It is furthermore likely, if the average "physical scientist" pays any heed at all, that he will devise a series of "tests" and "experiments" of his own, to fit his preconceived notion of things psychical, with the latent conviction, at least, that he will be able to prove the whole thing a humbug. These, also, are doomed to disappointment. Physical tests of psychical and spiritual laws and processes are unscientific. No spiritual problem can be solved in terms of physical matter alone. So-called psychological science to-day is in the condition of one possessing a fine piece of ground, and gathering materials for a house, a superstructure. The ground is already covered with bricks and stones, and sand and lumber, piled in every direction, with the purpose of one day beginning the work of construction, and the slogan, "Wait! Not yet!" "Some day we are hoping to build."