Overview of the Five Books of Psalms

In the first Book of the Psalms, we have Christ in association with a suffering but faithful remnant in Judea. Jehovah is the most frequent title used in this portion, being His title of covenant relationship with Israel. “To the saints that are on the earth, and to the excellent thou hast said, in them is all my delight” (Psa. 16:3 JND). The first two Psalms are introductory to the whole collection; they introduce the godly remnant and the Messiah—the Lord’s anointed (Psa. 2:2).
In the second book, the remnant is viewed as driven from the land but cheered and sustained by the presence and promises of their Messiah. God does not publicly own this remnant and so “God” (Elohim), the creation title, is used in preference to “Jehovah”. “God is our refuge and strength, a very present help in trouble” (Psa. 46:1).
The whole nation in the last days is spoken of in the third book. Their history and God’s dealings with them are referred to (for example, Psa. 78). The subject is taken up in a general fashion; it is not Christ in association with the remnant. We see equally references to “God” and “Jehovah”.
In the fourth book, we have the coming of the Messiah, the relationship between Israel and God having being restored. Jerusalem is the setting. Here we have the blessing associated with His reign and personal presence. These are joyous Psalms. Jehovah is again the preferred title. “O sing unto the LORD a new song; for He hath done marvelous things: His right hand, and His holy arm, hath gotten Him the victory” (Psa. 98:1).
The psalms that make up the fifth book are moral rather than prophetic, dealing with Israel’s return to Jehovah and His ways with his people (for example, the fifteen Songs of Degrees; Psa. 120-134). They end in praise.