There should be support behind the sofa: the so-called support means that there is a solid wall behind the sofa that is reliable and has no worries, which is in line with Feng Shui. It is for this reason that natural marble is chosen as the backrest for the chairs used in the courts in past dynasties, and the patterns on it had better have a faint mountain view.
If there are windows, doors or passages behind the sofa and there is no solid wall to rely on, it means that there is no backer behind it, it is empty and it is difficult to make a fortune. And psychologically, the back of the sofa is empty and insecure. As the predecessors said, "Look from all directions and listen from all directions". Because you can't observe the last two roads, if there is a door or passage behind the sofa, you should be more worried about being attacked behind it. It is best to sit with your back against a solid wall and feel very comfortable.
To take a step back, if the sofa back is really not as reliable as the solid wall, a more effective and convenient way is to put a low cabinet or screen behind the sofa, which can be called "artificial backer" and will also play a remedial role.
But it must be noted that there can't be water behind the sofa, so putting the fish tank behind the sofa is a no-no. In the same way, the low cabinet behind the sofa should not be equipped with decorative furnishings with water such as fish tanks and feng shui wheels. Of course, if the sofa without support at the back is full of evergreen plants, it is also beneficial and harmless.