expression, nidan verb (upper class) with 'tsu' ending (archaic)
to think of something bizarre; to suddenly have a whacky idea
Archaic literary expression using the classical verb 落つ (おつ). The modern equivalent is 奇想天外より来る (きそうてんがいよりきたる), which uses the classical 来る (きたる). Both are rare and found in older texts or stylized writing.
See also: 奇想天外より来る
The phrase 奇想天外より落つ, found in old writing, expresses the sudden occurrence of a bizarre idea.
A variant using the classical verb 来る (きたる) instead of 落つ (おつ). Both are archaic and rare, but 来る may be slightly more common in later texts.
The phrase combines 奇想天外 (きそうてんがい, 'fantastic, bizarre') with the classical verb 落つ (おつ, 'to fall'), literally 'to fall from the bizarre heavens'. The exact origin is uncertain, but it appears in older literary works as a stylized way to describe a sudden strange idea.