Simplify the following text for a Grade 6 native English-speaking person.
Original: He began conducting at the Casino in Montreux in 1912 , and from 1915 to 1923 was the conductor for Diaghilev 's Ballets Russes .
Simplified: In 1912 he began conducting at the Casino in Montreux . From 1915 to 1923 was the conductor for Diaghilev 's Ballets Russes .