how good and how pleasant

Today, driving home from a visit to my sister on campus (yes, she does live at home, and, yes, I did just see her this morning; but sometimes it's nice to visit her anyway), I was thinking about Psalm 133:

Behold, how good and how pleasant it is

For brethren to dwell together in unity!

It is like the precious oil upon the head,

Running down on the beard,

The beard of Aaron,

Running down on the edge of his garments.

It is like the dew of Hermon,

Descending upon the mountains of Zion;

For there the Lord commanded the blessing--

Life forevermore.

and I was mulling what it all means. How do brotherhood and unity relate to eternal life? What purpose will our unique personalities serve in Heaven? How is precious oil like dew?

(That up there at the top is Mt. Hermon.)