Ok, what is the blessing in this passage of scripture? Is it the green pastures? The quiet waters? How about the restoration of our souls? We would agree that the valley of darkness isn't the blessing. But, what about the table set for us before our enemies?
It is clear that while many of these can be looked upon as blessings, they are not the primary blessing revealed to us by the Psalmist. The primary blessing is our Shepherd. The Shepherd is the constant throughout this Psalm and throughout our lives. No matter what the circumstance, our Shepherd is always right there with us - through the good and the bad. He is the constant and He is the ultimate blessing.
When we have our Shepherd, we lack nothing and we want nothing, because He is our everything.