I like the idea of :1 and :$, but how do you get it to work in conjuction with selections (visual mode)? If I want to select the entire contents of the file, h

I like the idea of :1 and :$, but how do you get it to work in conjuction with selections (visual mode)? If I want to select the entire contents of the file, hitting "v" then ":1" seems not to work.