in the english language we can create an infinite number of sentences, even though we have a set number of words and grammatical rules. we can create infinite sentences because of the rules of recursion and iteration. the rule of recursion is how we come to center embedding by embedding one sentence within another sentence. linguists say that center embedding could go on forever and technically be grammatically correct. the reader would however become confused trying to keep track of who did what and when because our working memory would not be able to store and keep track of all the information. given enough time and a piece of paper and pencil, the reader could work out the information until the sentence made sense.