List of the twenty top-ranked words according to degree of fractality (left) and the first twenty frequent words (right) from the book The Origin of Species.

Words with high degree of fractality are important words according to subject of the book and common words have low degree of fractality. The string un which is placed in the second row of list of top-ranked words is a French determinant which appears four times in a single sentence. So, it is highly clustered and has high value of fractality. Because we do not perform any pre-processing to eliminate foreign words, this word appears in the list.