The Sufis (https://en.wikipedia.org/wiki/Sufism) consider nothingness to be the fifth element of nature.
The fifth element is synonymous with "void" or "sky", ie "空".
For a slightly abstract and colorful philosophy of martial arts, you may enjoy Miyamoto Musashi's Book of Void. https://en.wikipedia.org/wiki/The_Book_of_Five_Rings
It is more related to Aether in its Sanskrit origins. "आकाश"
If you're willing to make a linguistic leap, you could argue that "nothingness" or "無" constitutes the essential foundation of modern Japanese philosophy or philosophical Buddhism. https://plato.stanford.edu/entries/kyoto-school/
TIL Shamil[1] was a نقشبندية Sufi, probably one of the few to have his own ניגון tune[2].
[1] of whom I am always reminded when people in the US write about being "caucasian". Here are actual caucasians:
https://www.youtube.com/watch?v=JTdXQabTTRg
Consider:
https://www.youtube.com/watch?v=DmLfnWwP0g0&t=280 (4:40 to 7:00)
IIUC (and with apologies to Grothendieck), Ishida succeeded at 3-dan with a fire spirit, overpowering his opponents. At 8-dan, however, the examiners are looking for the void spirit.
A fire spirit cracks a nut by using a hammer and chisel, striking as needed until the shell cracks.
A void spirit gets the meat by immersing the nut in a softening agent until hand pressure suffices to decorticate, like a perfectly ripened avocado.