The composer Zoltan Kodaly was one of the great musical educators of the 20th century and he set up schools in his native Hungaryto teach his unique approach. He believed that learning music was a route through which emotionally, spiritually and intellectually well-rounded human beings could be nurtured. Ivan Hewett goes to Hungary to find out more about how and why Kodaly developed his musical-teaching philosophy and considers whether it has stood the test oftime. Producer Rachel Hopkin