Among the Greeks the theory of music was highly developed. In the 6th century bc the mathematician Pythagoras accurately determined the numerical relationships between strings that produced tones of different pitches. The Greeks selected and arranged the tones in scales called modes. Two of these Greek modes supplied the foundation for the music of the Western world. Choruses played an integral part in the ancient Greek dramas, sometimes singing as well as speaking. Poet-musicians competed at religious festivals. The amateur players accompanied their poems on the lyre, and virtuosos used the cithara, a similar instrument with more strings. 2. The development of Western music was intertwined with the growth of the Christian church. Chanting