“…Recovery of spectral accuracy in the presence of shocks and other singularities has become a "big business". A partial list of other efforts to accelerate Fourier series include [31,9,32,30,29,28,27,24,25,23,22,21,20,17,36,19,40,39,41,42,43,44,51,45,2,3,47,48,61,54,52,70,71,57,67,68,11,10] It therefore seems worthwhile to give a simple proof that this "spectral recovery" is founded on stone instead of sand.…”