The genes from our parents are united in our creation. Those genes are arranged in a way that is unique to us. That creates a person whose abilities physical and mental are bound to be different from all others. This presents us with a dilemma. In spite of the fact that we are similar to others in many ways, we are also different from others. Without a long term detailed, and time consuming inventory, we have no real idea of where the similarities and differences are.
This make it difficult to safely use phrases such as: "I know what you mean." When we say, "This really tastes good and you'll love it," we have made a high risk statement. And added to this problem is the fact that we build our own world through contact with things outside our skins. Those worlds are different.
Now think how difficult the task is to communicate with those around us, especially those we would like to be close to or work with/for. In order to build communities we gather in groups and hammer out ideas such as democracy or free speech. Those ideas have no real referent in the physical world. That makes them abstract. Abstracts, since they have no reference that can be touched, smelled or measured thus proving their existence, must be thoroughly examined, discussed and tested by most, if not all the community, in order to make it work.
Making the whole situation even more difficult is the fact that we all change over time. The changes, due to the new and different experiences that impact us, cause us to view the familiar in new and different ways. These changes over time makes it increasingly important that we never think that we have "finally settled that matter once and for all." Not unlike the student that says, "When I've finished this degree program I'm finished with school."
The whole area of human communication merits our complete and continuing attention. It is and should be one of the most consuming activities we attempt. The next time someone one, anyone, suggests that communication is simple, you are in the presence of someone doesn't understand communication.