The Inner Voice of Love is a collection of "spiritual imperatives" which Nouwen wrote to himself while going through the most difficult period of his life. This is his "secret journal," written during Nouwen's own dark night of the soul -- a time when he had lost his self-esteem, his energy, his sense of being loved, his hope in God.
To ingest and digest these imperatives (at least for me), I first need to read while imagining Nouwen writing to himself, to imagine what he was feeling, what he might be saying to himself. Only then can I read it again and ask myself, "Might this apply to me? Might I write this to myself? Might Henri say this to me? Might the Spirit of Christ (the Spirit of Love, the Inner Voice of Love) being saying it to me?"
Here's an example:
Understanding the Limitations of Others
You keep listening to those who seem to reject you. But they never speak about you. They speak about their own limitations. They confess their poverty in the face of your needs and desires. They simply ask for your compassion. They do not say that you are bad, ugly, or despicable. They say only that you are asking for something they cannot give and that they need to get some distance from you to survive emotionally. The sadness is that you perceive their necessary withdrawal as a rejection of you instead of as a call to return home and discover there your true belovedness. (Nouwen, p. 13)
Don Postema (in Space for God) suggests beginning one's morning prayer discipline with about five minutes of meditation -- simply and quietly repeating the phrase, "I belong to God." This may be the spiritual practice which, over the years, has been most significant in helping me to return home to God. Sometimes people talk about "going home" with respect to the death of a loved one. But I think we need to return home to God, to return home to the place of our belovedness in God each and every day. That's what Nouwen means when he talks about the call to "return home."