Section 22.3 Key Relationships
In the Baroque and Classical eras, composers typically modulated to the dominant (when starting in a major key) or to the relative major (when starting in a minor key). In the Romantic era, composers experimented with modulating to more remote (or perhaps adventurous) key areas, described as “foreign” to the home key.
“Closely related” keys have key signatures one degree “sharper” or “flatter” than the starting key. For any major or minor key, there are five closely related keys, including the relative major or minor of the home key.
Key signatures that are not closely related are said to be “foreign” or “distantly related.” We will see that some types of modulations from the Romantic era, like common-tone modulations, exploit foreign key relationships to dramatic effect.