"Buffalo buffalo Buffalo buffalo buffalo buffalo Buffalo buffalo." is a grammatically correct sentence used as an example of how homonyms and homophones can be used to create complicated constructs. It has been discussed in literature since 1972 when the sentence was used by William J. Rapaport, currently an associate professor at the University at Buffalo. It was posted to Linguist List by Rapaport in 1992. It was also featured in Steven Pinker's 1994 book The Language Instinct. Sentences of this type, although not in such a refined form, have been known for a long time. A classic example is the proverb "Don't trouble trouble until trouble troubles you".