Lucia VO (1960) tried to locate a "center" that will enable us to reproduce the patient's movements on a suitable articulator and execute our work more intelligently and with greater ease. He believed to locate the center, it is necessary to reduce the jaw movements to their simplest form. There is only one hinge axis. By locating the hinge axis, the center of vertical movement of the mandible is located. This enables us to place casts of the mouth on an articulator which will duplicate the opening and closing component of movement.