"The LORD is my shepherd, I lack nothing"
The first thing for us to take note of is the opening two words "The LORD". Who is "the LORD"? This is Yahweh. He is the I AM. He is eternal, he has always been and will always be. He is everlasting and there is no one and nothing like him. He is almighty and all powerful. He is the creator and sustainer of all things. He is the one who put Pleiades and the Horse Head Nebula in place, who created the atom and all its component parts, and he holds everything together. He is the sovereign ruler of the cosmos. He sits enthrone in the heavens right now in glory and splendour and power and majesty and might.
And David continues, as if that isn't enough, He "is my shepherd". This almighty sovereign God "is"; present tense, right now, at this very minute "my shepherd". Yahweh is my - this Psalm speaks of an intensely present and personal truth. David knows God is his shepherd. I can say my son is my son in a unique relationship that no other man on the planet enjoys with my son, there is a bond, he is my son. So the Psalmist can say that he has a unique and special relationship with the almighty sovereign of the universe. Yahweh is his shepherd. David places himself in the position of a sheep, one of the shepherds flock enjoying his care and love and guidance and provision. David is in the role of a dependent, he is one of the sheep of God's pasture. And there is no more secure place to be because of who the shepherd is, the shepherd is Yahweh.
And because he is one of Yahweh's sheep he can say "I lack nothing". That is an astonishing statement from David who has known plenty of lack in life. On the run from Saul as his life is hunted David looks, to our eyes, to lack everything; physical safety, a home, a kingdom, friends, and so on. Later on in life he is faced with the potential overthrow of his throne by his own son Absalom, and has to leave Jerusalem taking little with him. David has known plenty of times when it looks like he is lacking to worldly eyes. But David knows that if God is his shepherd then he is being led exactly where he needs to go. That the shepherd will withhold from him nothing that is needful. Therefore wherever he is led he can say I lack nothing. I am exactly where God has in his plan and purposes for me to be.
As we go into our day our confidence is not in us it is in the one who is our shepherd too. Psalm 23v1 calls us to lift our eyes up and see Yahweh in all his splendour and place our confidence for the day in him. It calls us to remember that he is our Shepherd today, he isn't the shepherd he is my shepherd - he knows me and calls me by name. Today he orders my steps and I am one of his sheep. And that means that we will lack nothing. Today nothing will confront me that is not in God's plans for me to face, I will not for one moment slip outside of his care and love.