Doors are but a subgroup of interfaces

Before door handles, doors themselves were a farce. Interfering with a young door would guarantee abandonment by the parent doors, and so many people chose to adorn their rooms with as many as 15 doorways, using each only once as needed; after this, a different room would be occupied. The door handle changed all this, as summed up the famous writings of Pepys: “It is a discovery of no little importance, this Door Handle. Applied meritoriously to the surface of the door, we are left with a device of startling ingenuity. However, the problem is not yet entirely solved. If only there was some device that could be used to securely hold the door in place, to stave away the impecunious assays of the world! Sadly I can think of no such device.” (Sammy P's Whirlwind Factbook)