This 'trouble' consists, in the sermon, of one thing, one aspect of life in the world which is harmful or which places the burden on us to change (either ourselves, our society, or the world).
I will explore what 'grace' means as it applies to the third page in more detail in this post, but in short it refers to the action God is taking (and, on page three, has taken, in or behind the Biblical text) about the 'trouble' of the first half of the sermon. Since for Wilson the proper object of the sermon is God and one of the most important tasks of the sermon (for Wilson) is to inspire hope and a sense of mission in its hearers, and to do so theologically, then it is appropriate for the focus of a sermon to be what God has done and is doing (and for Christians, has done and is continuing to do through the death and resurrection of Jesus).
Page Three is a new page for many biblical preachers to contemplate. Page One, exposition, and Page Two, application, are so familiar to most preachers [that] they are like a field that has been ploughed, planted, and harvested many times. We know the land in its slopes and furrows, yet we may not notice that the plants we grow are mostly from the seeds of trouble. Moreover, the harvest we gather and place on the backs of our congregation during the sermon makes their steps more laboured as they leave church - and this too we may not have noticed. Too often we explore the depth of human trouble and cast members on their own resources and abilities to make the necessary changes without identifying the help that God offers. Normally, when a child does something wrong, what good parent first kisses and hugs the child and then scolds There is commonly an order to be followed: from instruction to affirmation, from correction to embrace. The same is true when God deals with God's children. At minimum, there is a theological movement from brokenness and trouble to restoration and grace. .... In the sermon we mark this movement by moving to Page Three. [p. 156]The first two of Wilson's 'pages', then, are familiar ground. A lot of sermons refer to God's action not at all or at best scantily; it is up to us, they seem to say (see, for example, his discussion of the content of a collection of sermons on pp. 159-60, 161). For Wilson, the burden upon us to change our ways is only one half of the story.
Since the lack of grace in preaching is such a common problem and is the most important problem in sermon composition, Wilson spends a lot of time discussing it. He lists eight ways in which preachers fail to preach grace (pp. 161-4) and gives a practical example of a student of his who couldn't find what was graceful (literally) in her text on pp. 164-5. A lot of the time, grace is mentioned but only briefly, timidly, or obliquely.
Speaking from my own experience (for what it is worth), I have found, since I've begun using Wilson's method, that a lot of people have trouble hearing grace. (After all, grace means God's action, which means we've lost control of the situation; as burdensome as trouble can be, when it is 'up to us' at least we can pretend we're in charge of things.) I recall preaching several times at one placement and, when receiving feedback about each sermon, hearing the people repeat 'trouble' parts back to me, while rarely or else only briefly mentioning the grace. Of course, to be fair, I expect that I was not preaching grace very well, despite using Wilson's method. Even in my most recent sermon I imagine I would find that the content of my pages three and four would be much less well composed than the content of my pages one and two. Yet I still find that people have trouble listening to grace, no matter how well or poorly the preacher composes the second half of the sermon.
So much for that digression. Wilson has some interesting points to make for composing 'page three' of the sermon. As you might expect, he returns to the metaphor of film-making:
Use imagination to ask questions of the text. Use historical-critical scholarship [a variety of biblical scholarship which focusses on the historical context of a Biblical text] to answer these questions, the way movie directors rely on research to make the scene authentic to the times, geography, and customs [they do?]. Put in interesting sights and information that listeners might not otherwise encounter, not as commentary apart from the movie, but as part of the presented life and action. Again, the purpose is to keep sustained congregational focus on the biblical text. David Buttrick explains the problem: "While in one-to-one conversation, we can say 'God is a mystery' in the wink of an eye; to form the same understanding in group consciousness - oriented, imaged, explained - may take three to four minutes!" [p. 166]Along a similar vein, Wilson writes:
The focus of Page Three is God's actions in the biblical text. Find as many ways to use and to restate the theme sentence as possible. The congregation... must rely upon our repetition to discover the unifying principle of the page and to recognize its importance. Repeating and rephrasing the theme sentence is not enough, however; God must remain the subject of our sentences. Most students will state the theme sentence and quickly shift back to discuss human action. This takes the focus off God, however. [Such] sentences... can be recast, this time from God's perspective. [p. 168]Wilson develops this line of thought further on pp. 170-1 when he discusses the theme sentence. The theme sentence for the third page is, of course, the theme sentence, or statement, of the sermon, so the point of the repetition, of the development of the theme sentence, and of connecting it to the Biblical text being preached is to keep the preacher's, and the congregation's focus firmly on God.
In my sermon on Matthew 3.1-12, then, as I have stated, the theme sentence is God chose the people of Israel to be his people. So one factor to keep in mind when evaluating the sermon is how well I develop that sentence and how much I keep the focus of 'page three' on God.