That statement actually started back in history when people where becoming lawyers, doctors, teachers, and government officials. It was used when world was still a agriculture society and then also during the industrial revolution because people felt if you did not have rough hands and callus with scars then you did not work a real job. Today that has almost changed partly because industrial workers and farmers both wear gloves today to protect their hands. Also we have a lot of lotions and other hand care products that help the hands you not can tell as easy what a person's job by their hands as in the past.