As most of you know, Bruce Lee was very interested in Philosophy of all types.  While he attended school in Seattle, he majored in Philosophy.  He had a very extensive library that included books on many different styles of martial arts as well as several books by both contemporary and modern day philosophers.   Among these books were those written by Alan Watts.   
Alan Watts, an Englishman, was most widely recognized for his writings on Zen.  For more than Forty years, Alan Watts earned the reputation as a foremost interpreter of Eastern philosophies for the West.   In all Watts wrote more than twenty-five books and recorded hundreds of lectures and seminars, all building toward a personal philosophy that he shared in complete candor and joy with his readers and listeners throughout the world. His overall works have presented a model of individuality and self-expression that can be matched by few philosophers.
It's no doubt why Bruce held Alan in such high regards.
Following are brief excerpts from some of Alan Watts' writing.   

On NOTHINGNESS
        The idea of nothing has bugged people for centuries, especially in the Western world. We have a saying in Latin, Exnihilo nuhil fit, which means "out of nothing comes nothing." It has occurred to me that this is a fallacy of tremendous proportions. It lies at the root of all our common sense, not only in the West, but in many parts of the East as well. It manifests in a kind of terror of nothing, a put-down on nothing, and a put-down on everything associated with nothing, such as sleep, passivity, rest, and even the feminine principles. But to me nothing -- the negative, the empty -- is exceedingly powerful. I would say, on the contrary, you can't have something without nothing. Image nothing but space, going on and on, with nothing in it forever. But there you are imagining it, and you are something in it. The whole idea of there being only space, and nothing else at all, is not only inconceivable but perfectly meaningless, because we always know what we mean by contrast.

On EGO
I find that the sensation of myself as an ego inside a bag of skin is really a hallucination.  What we really are is, first of all, the whole of our body. And although our bodies are bounded with skin, and we can differentiate between outside and inside, they cannot exist except in a certain kind of natural environment. Obviously a body requires air, and the air must within a certain temperature range. The body also requires certain kinds of nutrition. So in order to occur the body must be on a mild and nutritive planet with just enough oxygen in the atmosphere spinning regularly around in a harmonious and rhythmical way near a certain kind of warm star. That arrangement is just as essential to the existence of my body as my heart, my lungs, and my brain. So to describe myself in a scientific way, I must also describe my surroundings, which is a clumsy way getting around to the realization that you are the entire universe. However we do not normally feel that way because we have constructed in thought an abstract idea of our self.