In an essay my students and I read for class, the author writes "Gilbert and Sullivan" as something of a punchline. I understood the reference, and even chuckled at its use, but what I was thinking about most was the use of "and."
For some years now, I've wondered what the difference is between "&" and "and." There may be an accepted usage for each, but since I prefer to speak with ignorance on rational matters I have decided free of external influence, I shall now state how I think the usage differs. You let me know if you agree or disagree. Honestly, I'm getting much better at talking about absolutely nothing for a really long time. I learned it from one of my professors.
My decision, from this moment forward, is that I shall use "&" to join two commonly/closely-related entities. The syntactical purpose is to eliminate confusion in sentences that have lots of "and"s in them. For instance:
Civil War history teaches us the dynamics of color like black and white and blue and gray.
Pretend I have just descended in a UFO and learned English, but I know nothing about the American Civil War. How do I know what color dynamics my non-alien self just wrote about? How do I know the "black and white" refers to races of people and the "blue and gray" refers to the clothing of warring sides. I say, think of the aliens (or anyone else who may encounter confusion from lack of context). Use more &s.
Now try the same sentence on for size, using &s:
Civil War history teaches us the dynamics of color like black & white and blue & gray.
... or perhaps this other example, which also uses &s to establish which "and" joins two choices and which "&" joins one word & another:
When considering the creators of musicals, I like Gilbert & Sullivan and Rogers & Hammerstein the least.
True story by the way...