tl;dr: Dijkstra argues that programming in natural language is a misguided goal, because the perceived "burden" of formal symbolism is actually its chief virtue: it rules out nonsense and ambiguity that natural language invites. He points to the history of mathematics, which only advanced once it escaped verbal reasoning for formal notation, and suggests natural-language programming would simply force us to reinvent formal systems anyway. He closes by noting that such machines would likely be as hard to build as they would be to use.