Greidanus’ outlines seven legitimate ways of preaching Christ from the Old Testament.
Now he brings these seven to bear on Ecclesiastes 1:1-11
As he’s already noted, two of his seven, promise fulfillment and typology, are not applicable in the main to Ecclesiastes.
Here are scant summaries of how Greidanus treats the other five:
Redemptive-Historical Progression: the statement ‘there is nothing new under the sun’ seems to cast a melancholy pall over this search for meaning; Jesus self conciously presents Himself as something new. In His newness there is hope for life and eternity.
Analogy: the New Testament teaching of Jesus can be understood to echo the teaching of Ecclesiastes that there is no security or meaning in material possessions. Jesus points us beyond putting our store in this life, setting our heart not on that which perishes, but on the Kingdom of God.
Longitudinal Themes: the futility of toil reflects the curse located in Genesis, and finds relief in the call of Jesus, ‘I am the resurrection and the life.’
New Testament References: Romans 8 and the reference to creation subjected to futility and James’ reference to humnanity as breath or mist. (James is not directly Christological.)
Contrast: Paul encourages the Christian to remember that their labour in the Lord is not in vain. Jesus also affirms the fruitfulness of our lives in Him in John 15.
Note the way that aspects of these points overlap one another in places.
So, what we have here is not preaching Christ in a way that seems like the magician’s pulling a rabbit from a hat, but rather preaching the text in a way that demonstrates the continuity of the text’s thesis with the rest of Scripture; and also the way in which Jesus references that theme in both His own teaching, and how He references Himself as being the solution to it.
Greidanus then goes on to demonstrate how these various observations can be referenced in a single sermon on the passage.
Reading this done as well as this is helpful in developing skill in preaching the Old Testament.