(d) Practice focusing the attention upon some abstract subject--that is upon some subject of interest that may offer a field for mental exploration. Think about the subject in all its phases and branches, following up one by-path, and then another, until you feel that you know all about the subject that your mind has acquired. You will be surprised to find how much more you know about any one thing or subject than you had believed possible. In hidden corners of your mind you will find some useful or interesting information about the thing in question, and when you are through you will feel well posted upon it, and upon the things connected with it. This exercise will not only help, to develop your intellectual powers, but will strengthen your memory, and broaden your mind, and give you more confidence in yourself. And, in addition, you will have taken a valuable exercise in Concentration or _Dharana_. _The Importance of Concentration._ Concentration is a focusing of the mind. And this focusing of the mind requires a focusing, or bringing to a center, of the Will. The mind is concentrated because the Will is focused upon the object. The mind flows into the mould made by the Will. The above exercises are designed not only to accustom the mind to the obedience and direction of the Will, but also tend to accustom the Will to command. We speak of strengthening the Will, when what we really mean is training the mind to obey, and accustoming the Will to command. Our Will is strong enough, but we do not realize it. The Will takes root in the very center of our being--in the "I," but our imperfectly developed mind does not recognize this tact. We are like young elephants that do not recognize their own strength, but allow themselves to be mastered by puny drivers, whom they could brush aside with a movement. The Will is back of all action--all doing--mental and physical. We shall have much to say touching the Will, in these lessons and the student should give the matter his careful attention. Let him look around him, and he will see that the great difference between the men who have stepped forward from the ranks, and those who remain huddled up in the crowd, consists in Determination and Will. As Buxton has well said: "The longer I live, the more certain I am that the great difference between men, the feeble and the powerful; the great and the insignificant; is Energy and Invincible Determination." And he might have added that the thing behind that "energy and invincible determination" was Will.