Debussy wrote wonderfully for the voice, making the music just right for the rhythm of the French language. This can be heard in his songs and his opera. Using melodies and harmonies which are often quite simple he creates a special kind of dream-world which can be very powerful. He often uses the whole tone scale and the pentatonic scale which give the music a hazy feeling because it does not seem to be clearly in one particular key. He liked to use unusual chords just for their own sake, not in order to make them lead to a particular key. He also used the old scales known as the church modes.