In plain words
In the principle called brahmacarya we must follow its order, keep divinity before us, first bring purity into the body, and go on experiencing it as it should be. Purity of body, purity of mind, purity of citta, purity of action: brahmacarya is made of just these four purities. Whatever you do, offering it with the feeling of Brahman is true brahmacarya. Of the things we need in life, the most important is food. Without this food there is no life at all. That is why life has taken the form called annamaya. But it is not man's nature to eat food and be satisfied. Merely filling the stomach does not fill the mind. Merely filling the mind does not bring life fulfilment. So though food is for the body, Ānanda is essential for the mind. Only a life joined with Ānanda is a full human life. So man does not like to eat and simply sit. He must work again and again. As we work again and again, we must ask ourselves: why are we doing this work, and how are we doing it? When we ask in this way, that action enters a pure path. Why am I doing this work, in what way am I doing it, what is its purity: only when we inquire into these three can we succeed in that work. This thinking gives the chief pointers in a human being's life. Thoughts must run in the right way. You must inquire into this thinking too: whether these thoughts are merely useless, or useful. And you must strive to develop the works you firmly believe to be good.
Our thoughts and conduct are the root cause of today's unrest
Entering into the best of works, cultivating the best of feelings, living the best of lives: the very first step to this is brahmacarya. At such a time we must cultivate divine feelings and develop fragrant thoughts; we must follow paths that unsettle no feeling of any kind.