What does it mean to leave three feet behind a seven-foot mallet?

South Fujian proverb: refers to everything to give people room. "Seven feet of the hammer to stay three feet back", this southern Fujian saying is to lift more than a dozen pounds of sledgehammer smashing stone, lifting method is a delicate - must be seven feet of the hammer to stay three feet back. Powerful hand holding the middle of the hammer handle to lift up, the other hand holding the tail downward pressure, lifted to a certain height and then smashed down, will have the maximum force to play out. Sledgehammer lifting method is in line with the principle of leverage, the center of a hand holding the fulcrum, after a hand holding the point of force, the head that is the focus of the most labor-saving lifting.

This phenomenon of lifting the hammer - seven feet of the hammer to stay three feet back, was compared to "everything to stay back, do not stay back, things will be difficult to do." Like lifting a sledgehammer, both hands are holding the tail of the handle is difficult to lift.

Similar to this, there is also a Minnan saying, "You can't show all the potential", "potential" refers to the strength, talent, wisdom and other human instincts, "show" is to show. It is also said that everything should be left a certain way back.