It is observable that the Holy Spirit, in some of the Psalms, has a twofold aim
and intendment, the one more immediate and the other more ultimate. They
have respect more immediately to some person that is an eminent type of
Christ. But their principle and more ultimate respect is to Christ
himself. So many of the Psalms have a more immediate respect to David; but
the main respect is to Christ, the son of David. So some of the Psalms
have a more immediate respect to Solomon, but ultimately respect Christ,
(Sermons and Discourses, 1739-1742, available
The importance of recognizing this christocentric principle is in understanding the main thrust of the Holy Spirit is to communicate truths about Christ, his reign and his kingdom, and not necessarily about Solomon's kingdom. By reading the Psalm christocentrically, Edwards understands that the blessings of the psalm are eschatologically focused.
Jesus comes down from heaven like rain from the sky. Jesus's heavenly person and benefits become the priority of the psalm. Just as the grass is nourished and quenched by rain from the sky, so believers are nourished and refreshed by his heavenly presence and work. This presence is twofold: first, in the incarnation of the first advent and second, in his coming in the second advent on the great day of judgment. The result in one of his applications is to encourage believers, because they have experienced the blessing of Christ come down from heaven, to forsake worldliness and renounce the vanity of exaltation in this life. Life in Christ is a life of humbly looking to Christ and not the world or the self for one's blessings and for righteousness. Look to Christ who alone can revive the soul and be refreshed!
Edwards christocentric reading naturally leads to the eschatological unfolding of the Psalm. Now, if only Edwards would have applied this to every psalm! If only he could have read Vos.