The type of feeling of confusion and distrut for your sense that some Koans attempt to instill.
Ciro Santilli's preferred version of it is physics and the illusion of life.
Some notable references:
- kotobank.jp/word/大疑-556655 quotes passing referenes by
- Nichiren (1272)
What should I do?
- Sasamegoto (1463-64)
The square is without Daigo because there is no doubt
- Nichiren (1272)
- en.wikipedia.org/wiki/Hakuin_Ekaku#Taigi_%E2%80%93_great_doubt mentions Hakuin Ekaku's take