In a recent [blog post][1], Lieven le Bruyn, discussing an interview with Connes, Caramello, and Lafforgue on *France Culture*, wrote > Towards the end of the programme Connes, Caramello and Laforgue [sic] lament that topos theory is still not taken seriously by the mathematical community at large So, what do they mean by saying topos theory is not taken seriously? [1]: http://www.neverendingbooks.org/yet-more-topos-news