Grothendieck (if it is was him) said somewhere :
"
This xxx is XXX, at least, is an idea that will not be used in physics"physics.
Q1 : is ?? Is XXX an n-groupoid, ? a stack? Can you supplies someone supply the precise quote? (, either in French or in Englishit does not matter).?
Q2: Predecessors of this quote in the same vein quotes would also be of interest? . Thank you.

