A few brief explanations are all that is necessary with a sutra as easy to apprehend as this one; intellectually its meaning is clear; in practice, however, it is difficult to carry out.

1. The internal organ is of course the mind. Occidental thinkers should remember that the Eastern occultist does not consider the organs to be the physical organs. The reason for this is that the physical body in its dense or concrete form is not regarded as a principle, but simply as the tangible outcome of the activity of the real principles. The organs, occultly speaking, are such centers of activity as the mind, the various permanent atoms, and the centers of force in the various sheaths. These all have their objective "shadows" or results, and these resultant emanations are the external physical organs. The brain, for instance, is the "shadow" or the external organ of the mind, and it will be found by the investigator that the contents of the brain cavity have a correspondence to the aspects of the human mechanism found upon the mental plane. This latter sentence should be emphasized; [26] it conveys a hint to those capable of taking advantage of it.
2. Tireless endeavor means literally constant practice, ceaseless repetition and the reiterated effort to impose the new rhythm upon the old, and to efface deep seated habits and modifications by the institution of soul impression. The yogi or Master is the result of patient endurance; his achievement is the fruit of a steady effort which is based upon intelligent appreciation of the work to be done and the goal to be reached, and not upon spasmodic enthusiasm.
3. Non-attachment is the one thing that eventually brings all sense perceptions to perform their legitimate functions. Through non-attachment to those forms of knowledge with which the senses put a man in contact, they continuously lose their hold over him; the time eventually comes when he is liberated, and is the master of his senses and of all sense contacts. This does not involve a state wherein they are atrophied and useless, but is one in which they are useful to the yogi when and as he chooses and in so far as he chooses; they are utilized by him in increasing his efficiency in group service and in group endeavor.