III. _The mind is the instrument you must employ for the accomplishment of any purpose._ Acting on this third postulate, you have begun the consideration of primary mental operations with a view to evolving methods and devices for the scientific and systematic employment of the mind in the attainment of success. You have concluded your study of the first of the two fundamental processes of the mind, the Sense-Perceptive Process, and have learned to distinguish between seeing or hearing or feeling on the one hand and perceiving on the other. [Sidenote: _Acquiring Mental Balance_] Realizing this distinction and applying it to your daily life, you can at once set to work to acquire mental poise and practical self-mastery, the essence of personal efficiency. There never has been a moment in all your life when sense-impressions were not pouring in upon you from every side, tending to disturb and annoy you and interfere with your concentration and progress. Heretofore you have struggled blindly with these distracting influences, not knowing the elements with which you had to deal nor how to deal with them. [Sidenote: _Dissipating Mental Specters_] But the mask has been torn from the specter of distraction, and hereafter when irrelevant sights, sounds and other sensations threaten to interrupt your work, just stop a moment and consider. So far as you and your actual knowledge are concerned, nothing exists in substance and reality outside your mental picture of it. So far as you and your actual knowledge are concerned, all matter is simply thought, and you have never doubted your ability to dismiss a thought. It is for you, then, here and now, to decide whether you will harbor sensory pictures that impede your progress and allow them to harass and dominate you and interfere with the achievement of your ambition, or whether you will ignore these intruders and thereby annihilate them. [Sidenote: _How to Control Your Destiny_] Success is a variable term. In the last analysis, it means simply getting the thing that _you_ want to have. Whether you succeed or fail depends altogether upon your own attitude toward the external facts of life. You have within you a living Force against which all the world is powerless. You have only to know it and to learn how to use it. Learn the lesson of your own powers, the secret of controlling the selective and creative energy within you, and you can bring any project to the goal of accomplishment. In the closing volumes of this _Course_ we shall instruct you in practical methods by which the selection of those elements of experience that are helpful may be made absolutely automatic. Transcriber's Note: Some illustrations have been moved from their original positions, so as to be nearer to their corresponding text, or for ease of navigation around paragraphs. Duplicate chapter headers have been removed from the text version of this ebook and hidden in the HTML version.