Combinatorial formation refers to the ability to form small phrases from different tonal elements. These phrases must be able to exhibit melodic, rhythmic, and semantic variation, and must be able to combine with other phrases to create global melodic formulas capable of conveying emotive meaning. Examples in modern speech would be the rules for arranging letters to form words and then words to form sentences. In music, the notes of different scales are combined according to their own unique rules to form larger musical ideas.