As regards the practices of concentration suggested in this letter, they are only stages in a life-long contemplation; they are means to an end, means of a certain order among means of other orders, all necessary, the highest path being that of constant devotion and entire resignation to the Law. The above means have a physiological value because the spots suggested for contemplation are, like others, vital centers. Excitation of these centers, and of the magnetic residue of breath always found in them, strengthens and arouses the faculties of the inner man, the magnetic vehicle of the soul and the link between matter and spirit. This is a form of words necessary for clearness, because in reality matter and spirit are one. We may better imagine an infinite series of force correlations which extend from pure Spirit to its grossest vehicle, and we may say that the magnetic inner vehicle, or astral man, stands at the halfway point of the scale. The secret of the circulation of the nervous fluid is hidden in these vital centers, and he who discovers it can use the body at will. Moreover, this practice trains the mind to remain in its own principle, without energizing, and without exercising its tangential force, which is so hard to overcome. Thought has a self-reproductive power, and when the mind is held steadily to one idea it becomes colored by it, and, as we may say, all the correlates of that thought arise within the mind. Hence the mystic obtains knowledge about any object of which he thinks constantly in fixed contemplation. Here is the rationale of Krishna's words: "Think constantly of me; depend on me alone; and thou shalt surely come unto me." The pure instincts of children often reveal occult truths. I heard a girl of fifteen say recently: "When I was a small child I was always supposin'. I used to sit on the window seat and stare, stare, at the moon, and I was supposin' that, if I only stared long enough, I'd get there and know all about it."