What is the fine-grained topic of the following text: The rich sustained string textures of the original transfer well to the manual and pedal of the organ, while the four-part harmony of the choir singing Arthur Sullivan’s well-known hymn tune ‘Onward Christian Soldiers’ create a sound world which is perfect as an introit or anthem. Only return the topic.
Organ and choir interpretation of Arthur Sullivan’s hymn 'Onward Christian Soldiers'