What is “the blues”?

Blues Pianist Memphis Slim had this to say:

It originated from slavery. That’s my opinion. It came from slavery. When a guy who was a slave wanted to say something that they really couldn’t say that would get them in trouble and they wanted to get back at their boss, they would sing.

The blues ain’t nothin’ but a botheration on your mind.

Blues bass/guitar/harmonica/piano player, singer, writer, and first black producer has this to say:

Well, frankly, the blues is nothing but the feeling when you got a good girl on your mind or something like that. But music has a good way of relaxing your mind against that feeling.

The blues is the roots and other music is the fruits