As Andrew Norman wrote, in a letter published in this book on page 113,  You flit freely back and forth between prescriptivism and descriptivism. 
( ( As ( ( Andrew Norman ) ( ( wrote , ) ( in ( ( a letter ) ( published ( in ( ( this book ) ( on ( page 113 ) ) ) ) ) ) ) ) ) ) ( , ( You ( ( ( flit ( freely ( ( back and ) forth ) ) ) ( between ( ( prescriptivism and ) descriptivism ) ) ) . ) ) ) )
(ROOT (S (SBAR (IN As) (S (NP (NNP Andrew) (NNP Norman)) (VP (VBD wrote) (, ,) (PP (IN in) (NP (NP (DT a) (NN letter)) (VP (VBN published) (PP (IN in) (NP (NP (DT this) (NN book)) (PP (IN on) (NP (NN page) (CD 113))))))))))) (, ,) (NP (PRP You)) (VP (VBP flit) (ADVP (RB freely) (RB back) (CC and) (RB forth)) (PP (IN between) (NP (NN prescriptivism) (CC and) (NN descriptivism)))) (. .)))
Andrew Norman says that you go easily switch to and fro from prescriptivism and descriptivism.
( ( Andrew Norman ) ( ( says ( that ( you ( ( go easily ) ( ( switch ( ( to and ) fro ) ) ( from ( ( prescriptivism and ) descriptivism ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNP Andrew) (NNP Norman)) (VP (VBZ says) (SBAR (IN that) (S (NP (PRP you)) (VP (VBP go) (ADVP (RB easily)) (VP (VB switch) (ADVP (TO to) (CC and) (RB fro)) (PP (IN from) (NP (NN prescriptivism) (CC and) (NN descriptivism)))))))) (. .)))