Agreed. They are the closest a machine can get to a living breathing organism - the "pant" of the compressor - like the breath of a beast, the beat of the exhaust - like its heart beat - the release of a steam valve - like its f#rt (sorry, this is a family thread)
And the whistle it's voice. I believe that they're mankind's oldest machine that has come closest to a living being. There's a reason why they're called 'The Iron Horse'.