why it fails is a riddle wrapped in a mystery inside an enigma . 
(ROOT (S (SBAR (WHADVP (WRB why)) (S (NP (PRP it)) (VP (VBZ fails)))) (VP (VBZ is) (NP (NP (DT a) (NN riddle)) (VP (VBN wrapped) (PP (IN in) (NP (NP (DT a) (NN mystery)) (PP (IN inside) (NP (DT an) (NN enigma)))))))) (. .)))
(ROOT (S (SBAR (WHADVP (WRB )) (S (NP (PRP )) (VP (VBZ )))) (VP (VBZ ) (NP (NP (DT ) (NN )) (VP (VBN ) (PP (IN ) (NP (NP (DT ) (NN )) (PP (IN ) (NP (DT ) (NN )))))))) (. )))