But we must not ignore our responsibilities. Trained thought is far more powerful than untrained, and therefore the more deeply we penetrate into Mental Science the more carefully we must guard against all thoughts and words expressive of even the most modified form of ill-will. Gossip, tale-bearing, sneering laughter, are not in accord with the principles of Mental Science; and similarly even our smallest thoughts of good carry with them a seed of good which will assuredly bear fruit in due time. This is not mere "goodie, goodie," but an important lesson in Mental Science, for our subjective mind takes its colour from our settled mental habits, and an occasional affirmation or denial will not be sufficient to change it; and we must therefore cultivate that tone which we wish to see reproduced in our conditions whether of body, mind, or circumstance. In these lectures my purpose has been, not so much to give specific rules of practice as to lay down the broad general principles of Mental Science which will enable the student to form rules for himself. In every walk in life, book knowledge is only a means to an end. Books can only direct us where to look and what to look for, but we must do the finding _for ourselves;_ therefore, if you have really grasped the principles of the science, you will frame rules of your own which will give you better results than any attempt to follow somebody else's method, which was successful in their hands precisely because it was theirs. Never fear to be yourself. If Mental Science does not teach you to be yourself it teaches you nothing. Yourself, more yourself, and yet more yourself is what you want; only with the knowledge that the true self includes the inner and higher self which is always in immediate touch with the Great Divine Mind. As Walt Whitman says:--"You are not all included between your hat and your boots." * * * * * _The growing popularity of the Edinburgh Lectures on Mental Science has led me to add to the present edition three more sections on Body, Soul, and Spirit, which it is hoped will prove useful by rendering the principles of the interaction of these three factors somewhat clearer_. XIV. THE BODY. Some students find it difficult to realize that mental action can produce any real effect upon material substance; but if this is not possible there is no such thing as Mental Science, the purpose of which is to produce improved conditions both of body and environment, so that the ultimate manifestation aimed at is always one of demonstration upon the plane of the visible and concrete. Therefore to afford conviction of an actual connection between the visible and the invisible, between the inner and the outer, is one of the most important points in the course of our studies.