A three-finger under actuated robotic hand with dexterous force control and inherent compliance is developed and tested. A simplified biomimetic finger design is generated and applied with mechanical intelligence principles carefully designed and embedded such that optimal trajectories for grabbing are naturally followed and the fingers can automatically conform to the goal object. A generalizable potential energy flow theory is then proposed to explain the mechanism behind the mechanical intelligence. The theory is also supported by experimental results. Quasi-direct drive actuators were developed to actuate the robotic hand with proprioceptive force sensing and inherent compliance. The hand performs delicate force-controlled manipulation with a simple compliance controller implemented.