The fourth book within the Book of Psalms contains #90 to 106. I am going on the idea that they may have been organized to reflect the Five Books of Moses. If that is factual Book IV corresponds to Numbers. It may be that David started this organization, but I feel that Hezekiah could have authored Psalm 102. So, we do not know who did the final editing of Psalms, but it has been this way for a very long time. More mysteries that we get to search out.
As I muse on the Books of Moses, I see them this way:
- Genesis is the creation of the world and the Hebrew people.
- Exodus is about freeing the people from Egypt and introducing how to be in the presence of God.
- Leviticus is for the priest to be able to help the people.
- Numbers, well, is numbers about the people and the numbers in the history of the trip.
- Deuteronomy is the second telling of the Laws and the trip.
Psalms 90 to 100 are thought to be from Moses and reflect what the former slaves needed to learn and remember. Psalm 100: 6 includes the name Samuel, which throws people into a tizzy. If Moses wrote these, Samuel could be one of many leaders that are not named in the Exodus. Psalm 101 is written by David. Psalm 102 is a prayer of an afflicted man; I think it was written by Hezekiah during /after he was healed. Psalm 103 is by David. Psalms 104 to 106 are unnamed, but they tell the history of creation (104) and 105 and 106 are very good recaps of the Exodus. Psalm 106 adds details that seem to be written after David, verses 40 to 48. I can hear this coming after Jeremiah, more likely it was written by Ezra or Nehemiah or beyond. The fourth book of Psalms does a good job of covering the history of Israel.