Proverbs, Ecclesiastes, and the Song of Solomon are the writings of King Solomon, the wisest of men. Not only did he receive wisdom and understanding from God—heavenly wisdom for an earthly pathway—Proverbs (1 Kings 4:29-34), but Solomon also received riches and honor (1 Kings 3:13).
In Ecclesiastes we have Solomon at the end of his earthly pathway, reflecting on his experiences. Having tasted every pleasure that this world has to offer—nobody can do more than the King can (Eccl. 2:12)—he declares “vanity of vanities; all is vanity” (Eccl. 1:2). There is no object under the sun that can fill the longing heart of man.
In contrast, the Song of Solomon presents Christ as the object of the heart. Here we have expressed the yearnings of one who desires an established relationship with the object of her love. It concludes with the triumph of love—“who is this that cometh up from the wilderness, leaning upon her beloved?” (Song of Sol. 8:5).
It is clear that all three books—Proverbs, Ecclesiastes, and the Song of Solomon—have a prophetic character. In them, we have, respectively, Israel in covenant relationship, the covenant relationship broken, and, finally, restoration.