The Heart Sutra (Prajna Paramita Hrydaya Sutra) talks about emptiness. It’s one of the most famous and important Sutras of all Buddhist writings. When people talk about Buddhism philosophy as a “philosophy of emptiness” it is this sutra they are referring to.
There is a Zen story that goes like this:
A young Japanese student of Zen, Yamaoka Tesshu was visiting one master after another. One day, he went to visit Master Dokuon of Shikoku with the intention of displaying his attainment. He was full of pride so he told the Zen master “The mind, Buddha, sentient beings, after all, do not exist. The true nature of phenomena is emptiness. There is no realization, no delusion, no wisdom, and no mediocrity. There is no giving and nothing to be received.” After he finished his statements he looked expectantly at Dokuon. The Zen master raised his hand and hit the young monk’s head. Yamaoka, feeling pain and anger asked, “Why did you hit me?” The Zen Master replied, “You said the mind, Buddha, sentient beings, after all, do not exist. If nothing exists, where did the pain and this great anger come from?” The young monk had no answer and could only keep silent.
If all is just like as this young monk said, “The true nature of phenomena is emptiness,” then why do we still feel pain, worried and suffering? I think is not that all phenomena is empty, rather it is that “all phenomena is ephemeral.”
I sometimes feel that Martial arts training is the same as practicing Zen. If you are well versed in sutra and but can’t use them in everyday life then why would you need to learn sutra? If you practice many different kinds of martial art forms but can’t use them in real applications then they are just show forms or exercise and not real martial arts.