 Our Master Mozi said, “Those in the world who perform tasks cannot do without models (fa) and standards. There is no one who can accomplish their task without models and standards. Even officers serving as generals or ministers, they all have models; even the hundred artisans performing their tasks, they too all have models. The hundred artisans make squares with the set square, circles with the compass, straight lines with the string, vertical lines with the plumb line, and flat surfaces with the level. Whether skilled artisans or unskilled artisans, all take these five as models. The skilled are able to conform to them. The unskilled, though unable to conform to them, by following them in performing their tasks still surpass what they can do by themselves. Thus the hundred artisans in performing their tasks all have models to measure by.”