A glorious thought! And yet, when you consider its proximity to the ultimate Union text (Col. 1:27), the implications become so glorious that we shouldn't be able to contain ourselves:
"[We] are those to whom God has planned to give a vision of the full wonder and splendor of his secret plan for the sons of men. And the secret is simply this: Christ in you! Yes, Christ in you bringing with him the hope of all glorious things to come..."
The answer to Paul's longing that we might "grow more certain in our knowledge and grasp of God himself" lives within us! The complete richness of "spiritual experience," our viewing of "God's great secret, Christ himself" - yes, He lives within us! "All the [hidden] treasures of wisdom and knowledge," the "full wonder and splendor of his secret plan for the sons of men," are bound up in the person and personality of the One who lives within us!
My friend, you already have everything you need to possess certain knowledge, a sure grasp, a rich spiritual experience, access to God's secret and hidden treasures, full wonder, splendor, the hope of all glorious things to come. It's all yours.
"And the secret is simply this: Christ in you!"