A couple of years ago I did a study on Psalm 117:

Praise the LORD, all nations;
Laud him, all peoples!
For his lovingkindness is great toward us,
And the truth of the LORD is everlasting.
Praise the LORD!

Sometime I’ll blog about my conclusions. In the meantime, let me make a very quick point.

Different parts of Scripture belong to different literary genres. The genre of a passage strongly affects how we are supposed to interpret it, primarily because the genre so strongly determines the purpose of the passage.

Lots of Scripture is written to inform its readers or engage them intellectually. In Romans, for example, Paul is explaining concepts to his audience and pressing home the logical conclusions they lead to. To get the meaning of Romans, it is particularly important to figure out what theological claims Paul was making, and then follow the thread of each argument.

Some Scripture is written to exhort its readers. For example, James is written not primarily to explain concepts but to call people to act. The exhortation involves information, but until we understand how its original audience would have heard it as exhortation we don’t understand it’s central meaning.

Psalm 117 is written to be expressed. It was given to Israel to be sung in worship. There is information (“His lovingkindness is great toward us”) and exhortation (“Praise the LORD”) but its primary meaning is not what is said to the Israelites, but what they were expressing for themselves as they repeated it in song. So to fully understand Psalm 117, we have to think about what it would mean to express it, not what it would mean to hear it expressed.

I suspect this is true for many of the Psalms.