Prayer can be described in a wide variety of ways. Nouwen addresses a number of views as he moves into the chapter.
First, he says that prayer is creating space for God (p. 18).
Life in the fallen world is filled with temptations to fill up every available bit of space with some occupation. As we allow this to happen we become preoccupied—distracted by the many voices, which drown out our ability to attend to the Voice.
In this section of the book, Nouwen is drawing on his training in psychology to show how unaddressed distraction eventually deteriorates into delusional living. We begin to ascribe elevated and unreal value to things which were never meant to hold that status. Or to say it another way, we make idols of people (even ourselves) and things (even our own accomplishments).
It is only as we pray that we detach ourselves from these artificial and counterfeit elements and give ourselves to an attentiveness to God. It is in prayer that we discover we are not in control. It is in prayer that we learn that we are not measured by our successes (or failures) or by our productivity (or lack of it).
We are defined by who we are in God. It is only as we pray that we come to see this and give ourselves to the implications which it provides.