"Madame Blavatsky... gave a caution that no one should attempt to use a mantra which is too high for him. None such will be given to us by our teachers; but I would say this, as a caution to neophytes, that if the reciting even of the Sacred Word (Om) in any particular way should produce headache or a feeling of nausea or faintness, it should be stopped at once. We should go on working at the development of our characters, and try it again in a few months. In using the Word, we are invoking great forces, and if we are not yet quite up to their level they may not be harmonious, and the result may be not invariably good. p. 149"