Along that line, where these rules are laid down for the organisation of the finer bodies, there is another matter that comes in: it is of no use to develop the finer bodies, unless the consciousness of the higher worlds is unfolded, and the only way to do that is by the old way of strenuous and regular meditation. Theosophy brings to the Western world the yoga of the East, by which the man who practises so trains and refines his brain that he makes it sensitive without making it diseased. There is where the difficulty is found in the West. Sometimes, when a great rush comes down from the higher worlds into the body of some great saint or some great genius, there is brain trouble and brain disturbance; hysteria is found. Naturally, because you are overstraining your instrument. And if you want to be able to receive those great downflows from the higher world, then you must begin to tune your instrument to vibrate to the swifter vibrations that come down. You can do it, and there is no danger unless you go to excess. If day by day you would give even ten minutes, or a quarter of an hour, to strenuous thought and careful concentration, you would gradually make your brain constitution more complex and finer than it is. Thought is really the creator of the brain. As you think, your brain grows; just as if you exercise your muscles, your muscles grow and develop. It is all law, and thought is the force which renders the brain more complex in its organisation. The Indian yogi practises that, and by practise year after year, builds up the brain of the coming race out of the brain of the race that is. He makes it finer, subtler, more responsive, and he does it without the sacrifice of physical health; and that is a thing that any one of you may begin, if only you will be moderate and not excessive. Never concentrate to the point of making a feeling of dulness and heaviness of the brain; never concentrate to the point of pain; dulness and pain are the danger-signals of nature, that you are trying to change matter more rapidly in its arrangement than is possibly consistent with health. Therefore you need moderation; but, given moderation, nothing but good can come out of the practise of meditation and concentration; and by that you will not only make your brain more sensitive, but also keep it sane and healthy, and you will have none of those miserable hysterical symptoms which have so blurred the value of the knowledge that has come through the seer or the saint. Along those lines, then, Theosophy works with science to show the road of development of science in the coming civilisation.