One is used to grind separate elements into a homogeneous mixture normally for potions, pills or guacamole. A kingdom often consists of unrelated, rough non pliable elements that need to be grinded to the finest particle in order for consistency and harmony. A king is a master alchemist that understands and sees the need for balance in all things even if the rest of the world doesn’t see it. A king also overstands that these things can’t be complimentary unless pressure is applied to bring out the regalia in each entity. Pressure makes diamonds as well as swords; what better sword is there than a kingdom for you to reign supreme?