If we are to understand prophetic task, we must begin with the prophet. Personhood sets the trajectory for performance. Character is always the basis of conduct. Brueggemann recognizes this when he says that the prophetic voice is rooted in something deeper than itself. The messenger is the pipe through which the message flows. So, we must begin with the personhood of the prophet. If we bypass this, we will almost certainly misunderstand and malpractice the prophetic task.
I want to note that while I will describe the personhood of the prophet in four ways: moral, mystic, mediator, and messenger, they are essentially parts of one whole, each interacting with and energizing the others. We gain insight by looking at the aspects, but the prophetic person is one even as God is One.
We begin with the prophet as a moral person. For Brueggemann, the root of prophetic imagination is its morality.  The prophet is a moral person who incarnates the message. Incarnation gives the message credibility, and it also means the message is liveable. Credibility and liveability make the message real. The prophets speak and enact the message to make it clear: God’s will can be done on earth as it is in heaven–the very thing we say in the Lord’s prayer. We cannot ignore reality, especially when it is Reality–that is, when it is of God.
Prophets are those who have integrated the message in themselves before communicating it to others. Brueggemann says this is exactly what happened to him prior to, and following, writing the first edition of The Prophetic Imagination in 1978. Between 1978 and 2001(second edition of the book) Brueggemann testifies to a process of formation in which his inperpretation of the prophetic imagination became increasingly incarnate in his own life. He does not hesitate to say that this integration enriched both his scholarship and his capacity to apply it to today–thus making the prophetic task contemporary and urgent, as it was for the original prophets  Brueggeman became a prophet through his study of the prophets.
Years ago, Henri Nouwen described authentic ministry this way: the minister is someone before he or she attempts to do some thing.  More recently, Richard Rohr has said essentially the sane thing, “Truth is a person.”  The prophets knew this, and lived accordingly. They stood as ensigns of the very truth they declared. 
Unfortunately, we have departed from this essential integrity/integration, creating a gap between our character and conduct. We are reaping the whirlwind of scandal as a result–and doing so currently in the political, religious, and entertainment areas of life. But as is always the case, personal and collective life is debased whenever performance (conduct) is separated from personhood (character)–when appearance eclipses authenticity. “Looking good” is not the same as being good. When we settle for “image” and ignore integrity, we pay a high and tragic price, individually and collectively. Immorality is one of the perils of empire as Brueggemann defines it. We will explore this further later in this series.
The prophetic task can only be studied legitimately in the larger context of the prophetic person. The prophet is a moral person, and only then can the message be genuinely holy. An old adage says it well, “Who you are speaks so loudly that I cannot hear what you say.” Personhood is the pivot that makes the message swing toward or away from God. The prophets knew this, and engaged in the prophetic task standing on the good foundation of morality.
 Brueggemann, The Prophetic Imagination, Second Edition, loc 84.
 The Prophetic Imagination, Second Edition, loc 64. I can only say that as I have been reading his books chronologically, I can see the “prophetic energy” (his term) growing in what and how Brueggemann writes. In a very real sense, he has become a prophet himself.
 Sadly, I have lost the reference to Nouwen’s words. If you happen to know the source, please email me (email@example.com).
 Richard Rohr, What the Mystics Know (Crossroad Publishing, 2015), loc 1439.
 The prophets were not faultless, but the were blameless. This is a critical distinction. To be blameless means they were faithful, inside and out, to the task. It does not mean they had no rough edges or made no mistakes. To be blameless is to live so that no accusation of infidelity can prevail. This is a covenant concept we will return to later–a theme that appears in the psalms (e.g. Psalm 15) and is echoed by the prophets (e.g. Isaiah 33:15). To lose this distinction runs the risk of making prophets “plaster saints” (Thomas Merton’s term)–“little saviors” (my term) who are driven by perfectionism and who fall prey to their own narcissism.