That you... may be able to comprehend with all the saints what is the width and length and depth and height – to know the love of Christ which passes knowledge; that you may be filled with all the fullness of God. (Ephesians 3:18,19)
The mark of a life governed by the Holy Spirit is that such a life is continually and ever more and more occupied with Christ, that Christ is becoming greater and greater as time goes on. The effect of the Holy Spirit's work in us is to bring us to the shore of a mighty ocean which reaches far, far beyond our range, and concerning which we feel – Oh, the depths, the fullness, of Christ! If we live as long as ever man lived, we shall still be only on the fringe of this vast fullness that Christ is.
Now, that at once becomes a challenge to us before we go any further. These are not just words. This is not just rhetoric; this is truth. Let us ask our hearts at once, Is this true in our case? Is this the kind of life that we know? Are we coming to despair on this matter? That is to say, that we are glimpsing so much as signified by Christ that we know we are beaten, that we are out of our depth, and will never range all this. It is beyond us, far beyond us, and yet we are drawn on and ever on. Is that true in your experience? That is the mark of a life governed by the Holy Spirit. Christ becomes greater and greater as we go on. If that is true, well, that is the way of Life. If ever you and I should come to a place where we think we know, we have it all, we have attained, and from that point things become static, we may take it that the Holy Spirit has ceased operations and that life has become stultified.
By T. Austin-Sparks from: The School of Christ - Chapter 1