These are only some of the major projects Sondheim worked on. Begining his training in classical music, Sondheim has to ability to compose for all instruments and to understand music theory. However, his composing style introduced unconventional musical concepts. He commonly used expanding harmonies, 9ths and higher. He also used note iterations, retrograde, dissonance, and chord progressions that do not follow natural cadences. Sondheim proved that defying the laws of music theory can create such a complex sound that can serve different purposes but are still useful. He also was unafraid to delve into the dark psyche of his characters and analyze the human mind in the 20th century. His work is original and introduced depth which superseded the previous notion that Broadway productions sought solely to entertain and shows could only succeed based on their commerciality. Sondheim's works are studied and produced to this day despite dealing with difficult motifs and social critiques. [2,6]