The person who wants only to be good pushes away everything grasping and cunning in himself. He calls that part dishonest and disowns it. But it does not vanish. It sinks out of sight and takes his practical intelligence with it, so he faces the world unarmed and is easily used.
The clever manager stands for exactly that buried side. The master praises him because survival needs the very shrewdness that pure goodness throws away. The children of the world can act because they still own their instincts. The good must take that discarded cleverness back, or they stay helpless.