The change in interfaces, particularly metaphors, is really interesting as things go from derivatives (e.g. a mechanised horse) to originals (e.g. a tractor).

The change in interfaces, particularly metaphors, is really interesting as things go from derivatives (e.g. a mechanised horse) to originals (e.g. a tractor). It's also interesting when metaphors don't change, failing to keep up with reality, e.g. the floppy disk being used a save metaphor, when floppy disks have not been prevalent for years.