When the mind is kept firmly fixed upon some ideal or aim, its whole and varied powers are bent toward the realization and manifestation of that ideal. In thousands of ways the mind will operate to objectify the subjective mental attitude, a great proportion of the mental effort being accomplished along sub-conscious lines. It is of the greatest importance to one who wishes to succeed in any undertaking, to keep before his mind's eye a clear mental image of that which he desires. He should picture the thing desired, and himself as securing it, until it becomes almost real. In this way he calls to his aid his entire mental force and power, along the sub-conscious lines, and, as it were, makes a clear path over which he may walk to accomplishment. Bain says regarding this: "By aiming at a new construction, we must clearly conceive what is aimed at. Where we have a very distinct and intelligible model before us, we are in a fair way to succeed; in proportion as the ideal is dim and wavering, we stagger or miscarry." Maudsley says: "We cannot do an act voluntarily unless we know what we are going to do, and we cannot know exactly what we are going to do until we have taught ourselves to do it." Carpenter says: "The continued concentration of attention upon a certain idea gives it a dominant power, not only over the mind, but over the body." Muller says: "The idea of our own strength gives strength to our movements. A person who is confident of effecting anything by muscular efforts will do it more easily than one not so confident of his own power." Tanner says: "To believe firmly is almost tantamount in the end to accomplishment. Extraordinary instances are related showing the influence of the will over even the involuntary muscles."