YES and NO

[Frans Plank]

for light entertainment in between the colours:

Is anybody out there aware of wide-range comparative etymological work on
words (well, sentences) meaning YES and NO which shows that these items
are, or were, morphologically complex?

This question has come up in recent discussion (most recently at the
Leipzig Rara event) of a paper by Johan van der Auwera (et al) on
person-number inflection (or clitics) being extended to YES/NO, as in Dutch
JAA-N-SE yes-AGR-they 'yes, they do'.

French OUI 'yes' was complex, supposedly deriving from HOC ILLE.
English YES is another one, deriving from YEA SIE 'yes, so it be'.
Or German NEIN, deriving from NOT ONE.

What are possible sources?  And is such morphological complexity destined
to quickly become opaque with such words/sentences?

Frans Plank