I think that Todoroki-san’s blog post on Sept 28th, is related to the concept of 漸近自然. Though maybe a little different.
Actually that blog post has 3 topics:
The nomenclature of a tenkara rod, the concept of Three Treasures in the Japanese language text. And in the English language text - thoughts on the things that influence the ideas of what Tenkara is or What is Tenkara. But I am focused on the ideas in the Japanese text in the blog post.
Tenkara Rod Nomenclature テンカラ竿各部名称
Wherein Todoroki-san writes, as best I can translate it:
After that (referring to the selection of a tenkara rod with the proper flex for the intended purpose)
Clothing and equipment that does not impair safety and health
Knowledge of mountains and streams that protect fish and myself (yourself)
Edible wild plants, mushrooms also the same
Things to do In gratitude and respect
I think that this is the real intention (Spirit) of Fuji Sudo (Shindofuji) ~~~
Three sacred treasures of fly fishing
Fishing rod / fishing line / kebari
Three sacred treasures of anglers
Body, knowledge, experience
Accept or respond to
Nature (or own nature) · river · fish
Both are a Trinity
(That three things are essentially one thing)
~~~ I am not quite certain how to translate Fuji Sudo or Shindofuji [身土不二].
身土不二 is a Buddhist concept. The weblio website defines it this way:
you are what you eat; slogan encouraging consumption of local seasonal foods for one’s health; indivisibility of the body and the land (because the body is made from food and food is made from the land)、inseparability of body/mind and geographical circumstances.
weblio 身土不二 Shindofuji
Google : 身土不二 の英語 … 身土不二 in English.
I think it is a somewhat similar to:
“A man is what he thinks about all day long”. - Ralph Waldo Emerson. Or -
“As a man thinketh in his heart, so is he”. Proverbs 27:3
iow - the idea that we are influenced by our surroundings; environment, mental / spiritual / thoughts/ attitudes, & experiences. Self determination by the places and ideas we choose to surround ourselves with. Choose carefully!
Google translates 漸近自然 as Asymptotic Nature. Asymptotic (an asymptote) being a mathematical concept where a curve approaches a line very closely, but the two never touch. Two functions approach unity as the two functions reach their limits. Which I think fits the idea of slowly approaching the unity of the 2 Three Treasures.