These two ideas stand out in Psalms 131 and 133. Two short Psalms introduced as Songs of Ascents, of David. Humility demands a reduction. A reducing of self, not an advancing of self. It is not self-promotion. This is Psalm 131 where David says, “O LORD, my heart is not lifted up; my eyes are not raised too high; I do not occupy myself with things too great and too marvelous for me. But I have calmed and quieted my soul, like a weaned child with its mother; like a weaned child is my soul within me.” (Ps. 131:1, 2). He takes the place of a child, completely dependent. This is humility.
In Psalm 133, David speaks of harmony. He speaks of expansion and liberality. An overflowing. He says, “Behold, how good and pleasant it is when brothers dwell in unity! It is like the precious oil on the head, running down on the beard, on the beard of Aaron, running down on the collar of his robes! It is like the dew of Hermon, which falls on the mountains of Zion! For there the LORD has commanded the blessing, life forevermore.” (Ps. 133:1-3). Unity is harmony. How pleasant it is. These two traits or attributes are facets that shine light upon the doctrine of the Church. The Church should be like this, and when it demonstrates humility and harmony, then it is at peace and filled with joy. It becomes a place of joyful service. How good that is!