... is the pressing to take away the necessity for skill in any job done by any one. The old-time tool hardener was an expert. He had to judge the heating temperatures. It was a hit-or-miss operation. The wonder is that he hit so often. The heat treatment in the hardening of steel is highly important—providing one knows exactly the right heat to apply. That cannot be known by rule-of-thumb. It has to be measured. We introduced a ... — My Life and Work • Henry Ford