You anoint my head with oil (Psalm 23:5b)
In Scripture, anointing with oil carried two purposes: to heal, both spiritually and physically, and to set apart for God's use. David, with his unique place in history, must surely have been referring to both uses when he sang of the Shepherd anointing his own head. David, who would be King, but who felt wounded physically, emotionally, and spiritually. It hadn't been that long ago, after all, that David was literally anointed by the prophet Samuel to become King over Israel.
It makes sense that anointing oil be used for the purpose of both healing and calling, and speaks to the way God chooses and cultivates those who will serve Him.
As humans, we are inheritors of the Fall, broken at birth. We are born into sin, into a world of disease and pestilence and death. We are, in short, born wounded -- physically and spiritually dying from Day One.
When we recognize we are the Shepherd's, and that He is our Lord, He anoints us for His use. Through His Spirit, He anoints us first for healing -- a balm and salve for our naturally broken state -- and then to set us apart. As David discovered, this is a part of the Joy of belonging to the Good Shepherd.
When we work for the World, we are used up and discarded. The world will take the best of us and, when it's through, leave us to die. But God isn't like that. God prepares us with a healing, and then marks us as one of His Own. So marked, the end of our walk on earth isn't merely death, but a homecoming. "You are mine," God says in His anointing. "Not just My sheep or servants, but my children."
Anointing, then -- in both its healing and sanctification -- is inclusion. Inclusion into the service, and the Family, of the Almighty.