In this battle drill is necessary. And that drill is the control over one's physical organs and over the faculties of mind. For if one is not prepared for this battle, however courageous and optimistic one may be, one cannot succeed. Another thing is to know something about this warfare; to know when to retreat and when to advance. If one does not know how to retreat and wishes always to advance, one will continually be in danger and become a victim of life's battle. There are many people who in the intoxication of life's battle go on battling, go on fighting; in the end they will meet with failure. Young people, strong and hopeful, who have had fewer difficulties, may think of nothing else but battling against all that stands in their way. They do not know that it is not always wise to advance. What is necessary is first to fortify the position and then to advance. One can see the same thing in friendship, in business, or in one's profession. A person who does not understand the secret of the law of warfare cannot succeed.