Practice is absolutely necessary. You may sit down and listen to me by the hour every day, but if you do not practice, you will not get one step further. It all depends on practice. We never understand these things until we experience them. We will have to see and feel them for ourselves. Simply listening to explanations and theories will not do. There are several obstructions to practice. The first obstruction is an unhealthy body: if the body is not in a fit state, the practice will be obstructed. Therefore we have to keep the body in good health; we have to take care of what we eat and drink, and what we do. Always use a mental effort, what is usually called "Christian Science," to keep the body strong. That is all — nothing further of the body. We must not forget that health is only a means to an end. If health were the end, we would be like animals; animals rarely become unhealthy.