The authority in question gives the following excellent advice regarding the subject of the development of clairvoyant power and astral visioning:  “Now the fact is that there are many methods by which it may be developed, but only one which can be at all safely recommended for general use—­that of which we shall speak last of all.  Among the less advanced nations of the world the clairvoyant state has been produced in various objectionable ways; among some of the non-Aryan tribes of India, by the use of intoxicating drugs or the inhaling of stupefying fumes; among the dervishes, by whirling in a mad dance of religious fervor until vertigo and insensibility supervene; among the followers of the abominable practices of the Voodoo cult, by frightful sacrifices and loathsome rites of black magic.  Methods such as these are happily not in vogue in our own race, yet even among us large numbers of dabblers in this ancient art adopt some plan of self-hypnotization, such as gazing at a bright spot, or the repetition of some formula until a condition of semi-stupefaction is produced; while yet another school among them would endeavor to arrive at similar results by the use of some of the Indian systems of regulation of the breath.  All these methods are unequivocally to be condemned as quite unsafe for the practice of the ordinary man who has no idea of what he is doing—­who is simply making vague experiments in an unknown world.  Even the method of obtaining clairvoyance by allowing oneself to be mesmerized by another person is one from which I should myself shrink with the most decided distaste; and assuredly it should never be attempted except under conditions of absolute trust and affection between the magnetizer and the magnetized, and a perfection of purity in heart and soul, in mind and intention, such as is rarely to be seen among any but the greatest of saints.

“Yet there is one practice which is advised by all religions alike—­which if adopted carefully and reverently can do no harm to any human being, yet from which a very pure type of clairvoyance has sometimes been developed; and that is the practice of meditation.  Let a man choose a certain time every day—­a time when he can rely upon being quiet and undisturbed, though preferably in the daytime rather than at night—­and set himself at that time to keep his mind for a few minutes entirely free from all earthly thoughts of any kind whatever, and, when that is achieved, to direct the whole force of his being towards the highest ideal that he happens to know.  He will find that to gain such perfect control of thought is enormously more difficult than he supposes, but when he attains it it cannot but be in every way most beneficial to him, and as he grows more and more able to elevate and concentrate his thought, he may gradually find that new worlds are opening before his sight.  As a preliminary training towards the satisfactory achievement of such meditation, he will find it desirable to make a practice of concentration