There is this book, "Living Opera," by Joshua Jampol. It is just a series of Q&A's but there are some interesting things in it. In other words it is like Goodwill. There is a lot to sift through but you find some good stuff.
One thing I liked is Placido Domingo, asked his opinion on critics.
"I have a lot of respect for critics when they have something constructive, something intelligent, to say. I don't like critics when they try to follow predecessors, the Bernard Shaw types, in being cruel, trying to be phony-smart. Yes, you can say things are not good; I don't mind. I might agree with them. That's one thing. But when they start to use cruelty -- and I'm not talking about me, I'm talking generally -- I have read a lot of them where they are enjoying themselves when they write. Sometimes also what you have is a review of eight columns, and seven columns -- if it's an opera by Verdi -- they are talking to you about Verdi, about Verdi's time, telling you about all the knowledge they have. Then, in the last column, they talk about the performance. And that's their review. If you're a writer, fine; write a book. But if you're a reviewer, concentrate on what you have to write. Even if it's a negative."
Well said, sir! Well said.
Grand opera this is not but here is some great vintage 1970s TV, complete with Sarah Brightman. The clip of Sarah and this other woman introducing the aria is priceless.