Those who know its value consider the training of the ego the most important thing in life. The first lesson in this training is to ask, "Why must I have a certain thing? Why must I not have it? If it is not good for me why should I have it? And if it is good for me why should I not have it?" What a person has acquired the habit of speaking with his ego in this way about every physical appetite, he will always be able to do what he ought to do.