Dictionary attack which defeats most simple substitution ciphers. Undeafeated ciphers after convergence probably require frequency analysis or something more sophisticated.
English dictionary is from: http://stackoverflow.com/questions/2213607/how-to-get-english-language-word-database which refers to http://www.infochimps.com/datasets/word-list-350000-simple-english-words-excel-readable (archived).
Rendered into JSON by: https://github.com/dwyl/english-words.git