I was a huge fan of the blog Cheap Talk. I say was only because the posting rate there has trickled down to almost nothing (sure, you could say the same thing about this blog, but I also have practically no readers). But, occasionally they still put up a new post that, more often than not, includes terrific passages such as this one:

So, is Hachette, a French company, confused because in France they put price on the x-axis and quantity on the y-axis so marginal revenue is upside down? Surely Jean Tirole can sort that out for you.