According to the Maxwell equations, maintaining a static magnetic field needs not additional energy supply into the system. The energy transformation occurred only if the magnetic field of the system is changed. This is the scientific principle to comprehend the permanent magnetism and has no any relationship with the perpetual mechanics. This theorem is identified by the lodestone that exists for thousands of years on the earth. The geographic magnetic texture is changed only if the lava extravasations occurred there and the lodestone was damaged.