This is referring to the fact that after the French revolution the people of France changed the way they spoke to sound more like how the noble class spoke. The French in North America were isolated from this and maintained the “original” way of speaking French.
Nowadays, to a Quebecer, Parisian French sounds pompous and snobbish, while to a French person, Quebecers sound unrefined and coarse.
I find it very strange as someone as comfortably far away from French Canada one can be while still being on the continent that I technically am described as French by this diagram. I failed French so hard in 8th grade my teacher passed me on the promise that I never take another French class.
Before the revolution, and for most of the nineteenth century there was hardly any common French idea. Like with most countries, community and tradition are recent inventions.
Graham Robb in ‘the discovery of France’ has the perfect analogy that a French dialect only carried as far as the nearest church bell. People a valley further would speak a different vernacular.
