[Wuli]

As again the last window we manage to pry open reveals a reality with more questions than we had before that window was opened.

The universe can’t ever be fully explained - it’s like an infinite onion; layers within layers, within layers ad infinitum.

[Red Badger]

There is always the question “What is that made of?”

[tet68]

an infinite onion; layers within layers, within layers ad infinitum.

It’s turtles all the way down.

[Alas Babylon!]

Shrek like an onion:

[cuban leaf]

i.e. the more wee know, the more we know we don’t know. ;)