During the first minute of his talk on Transcendental Meditation, filmmaker David Lynch refers to an "ocean of pure, vibrant consciousness" that underlies all matter. I do not practice TM myself, and the teachings of Zen Buddhism are different from those of the Maharishi Mahesh Yogi, but this "ocean of pure, vibrant consciousness" may be analogous to what some physicists mean when they say that all matter is like light - simultaneously existing both as particles and as waves, and more specifically, waves on an ocean of consciousness.
As we discussed at last night's Monday Night Zazen, Yasatuni Roshi states in The Three Pillars of Zen that the nature of everything is such that it can become Buddha. This nature is referred to as "Buddha-nature" which is the universal and all-pervasive potential for all things to to become Buddha.
"All phenomena are the result of the law of cause and effect," Yasatuni says. "They arise when causes and conditions governing them mature. When one of these causes or conditions becomes altered, these phenomena change correspondingly. When the combination of causes and conditions completely disintegrates, the form itself disappears. All existence being the expression of the law of cause and effect, all phenomena are equally this Law, this Dharma. . . Stated differently, all phenomena are transformations of Buddha- or Dharma-nature."
The substance of this Buddha-nature, Yasatuni explains, is called shunyata, or emptiness. But more than mere nothingness, this emptiness is the living, dynamic, and unfixed matrix of all phenomena, devoid of mass and beyond individuality or personality. And this living, dynamic unfixed matrix of all phenomena is but a field of potential - the potential for transformation according to conditions, the potential to become Buddha.
According to Buddhism, what we call "life" is no more than a procession of transformations. If we do not change, we are lifeless. All things are like this - an ever-changing arising and decaying of phenomena according to causes and conditions within a matrix of potential. There is no real substantiality or permanence beyond this; that is why the substance of Buddha-nature is called "emptiness."
The Buddhist patriarch Nagarujna once said that the mind that solely sees the impermanence of this world of constant appearance and disappearance is also called bodhi- (wisdom) mind. Yasayuni explains that when one truly understands this fundamental principal, "you will not be anxious about your life or your death. You will then attain a steadfast mind and be happy in your daily life. Even though heaven and earth were turned upside down, you would have no fear."
There's more I'd like to say, but I'm afraid I've said too much already. These things don't translate into words very well. Buddha-nature cannot be grasped by the mind, it transcends all conception and imagination. Whatever one imagines it to be is, by definition, imagination and not Buddha-nature itself.
But because we ourselves are intrinsically Buddha-nature, it is possible for us to awaken to it. When we quiet the mind in meditation and cut off all discriminating thought, mind and body can drop away and we intimately realize Buddha-nature. Thus, Zen Master Dogen says that practice is enlightenment.