Metaphors and Science

I wonder how many scientists have used metaphors as inspiration for their work. For some strange reason, my mind brought to mind metaphors connected to the mind which I didn't mind at all. "Single-minded" and being "of two minds" are the two in particular which came to mind. Was the concept of left and right halves of the brain in place before there was scientific evidence supporting it? When someone is single minded, does that mean they're ignoring one side of the brain (probably the right)?