How to Harmonize the Hymn Tune in Related Keys

Usually when we perform hymns on the organ, we play just in the main key, choosing the voice disposition with the melody in the soprano. But what would happen, if you played your harmonization in several closely related keys, putting the melody in the soprano, tenor, and the bass? This, by the way, is one of the first steps to improvise a real chorale fantasia. In this lesson, I will teach you how to do it.