The use of each key in Western music?

Question

I've been looking into variations on the following question: why was X piece written in Y key? For instance, why did Beethoven choose to write the Moonlight Sonata in C# minor? Presumably we can transpose a piece and, in theory anyway, it will still be the same. I know that this question has been asked before, but I'd like to expand on the previous questions asked by other posters. In particular: There are a number of opinions of composers about each key. C major is considered "innocent and childlike", for example, but one source refers to F-sharp minor as "A gloomy key: it tugs at passion as a dog biting a dress. Resentment and discontent are its language.". I disagree with that opinion on F-sharp minor (I find it to be a playful key in which dances "make sense"). So I suppose the question really is: how does a composer develop their particular style and thereby attribute certain desirable qualities to each key? For example, I've already chosen F-sharp minor to be a playful, dance-like key and G-sharp minor to be a slow, haunting key. That's my personal opinion, but I can't define why I hold it.

Answer 1

I don't think you have to define why you hold a certain opinion on what a key emotes to you. A part of the process of composition is being able to simply make those connections for yourself and the fact that you are doing that is indication (to me anyway) that you are on a good road. For me, E Major is often very bright (sunrise) while Eb Major is dark (midnight). Others might view it differently and that's ok. Our experience, thought, and musical background all shape how we compose music and to a great extent how we perceive music. As we grow and learn more about different kinds of music, some of our initial thoughts are solidified while others are drastically altered. It is all apart of a continuous process of growth we have as musicians. I hope that was somewhat helpful!