Shoeing a horse

He'd come from Florida to shoe the horses, to wield 28 years of knowing.  I asked him, Did he mind if I watched?  He said he didn't mind much.  I asked him, How is it that the horse does not flinch as each of those six, long, sturdy nails are driven into that one hoof?  He said, Think of the tip of your fingernail.  Would you feel it, if a nail were driven through?