Note that Backus's complaint is in relation to EWD638, where Dijkstra tears apart every claim made in a paper and accuses the authors of having a "pre-scientific attitude" and giving "the impression of anti-intellectualistic reactionaries". But none of this explains why the "provenance" of Alan Kay's statement about Dijkstra's arrogance is supplied in a retelling of Backus's statement about Dijkstra's arrogance. The provenance of Alan Kay's statement is that Alan Kay said it, in his OOPSLA keynote.