There are 15 psalms in a row, Psalm 120 through Psalm 134, that are labeled “Songs of Ascent” or some translations may have “Songs of Degrees”. Since I love to solve a puzzle I did a little research and found that these psalms were sung by a procession (usually of priests, followed by the people) as they went up the steps to the temple. Some sources say there were 15 steps from the court of the women up to the next court in the temple and the priests would chant the next consecutive psalm on each step. Very possibly the key changed, musically going a step higher as well.
Psalm 133 is used as a responsive reading in churches. It’s very short and seemingly obtuse on first reading it. Here it is, verse by verse:
1) Behold, how good and how pleasant it is for brethren to dwell together in unity!
Yes, yes, a good reminder especially if a church is going through any "unpleasantness". Actually King David wrote this psalm when he regained his throne after his son Absalom’s rebellion. The story is in 2nd Samuel and 1st Chronicles and tells how the people were of one mind to make him king and support him again – together in unity – and the Hebrew word for together and for unity is the same word and is repeated here so the verse ends with the same word twice. (How intricately woven is the word of the Lord.)
2) It is like the precious ointment upon the head, that ran down upon the beard, even Aaron's beard: that went down to the skirts of his garments;
Sounds kind of messy and oily, but as I looked up the recipe for this oil (Exodus 30: 25) I found that it contained myrrh and cinnamon and lemon grass and other great smelling herbs and I bet it was a very pleasing aroma, very different from the smells I suspect were common place then like sweat and rotting things and animals.
3) As the dew of Hermon, and as the dew that descended upon the mountains of Zion: for there the LORD commanded the blessing, even life for evermore.
This place called Hermon has really, really heavy dew, so here the psalmist is just coming up with a way to show how the Israelites’ unity was covering them all. I love the commanded blessing: life for evermore. This is a promise of eternal life.
Well, this is an incredibly short chapter - only three verses - but an awful lot is packed in there.