This is a very important observation because it represents a pattern of key relationships, which can be further extended to include keys that have three sharps, four sharps, five sharps, and so on (see Figure 19.1).
Each key whose tonic is a fifth higher requires a further sharp in the key signature.
Keys with sharps in them are often thought by musicians to be emotionally bright keys. The more sharps a key has, the brighter it is felt to be. Whether or not this is entirely subjective is difficult to say. But it can affect your choice of key for ...