We shall never really know Christ as He is to be known until we begin to tell what we already know. In the realm of religion we never really know until we testify. Until the disciple becomes an apostle he is never an advanced disciple. Every teacher knows this; his knowledge grows while he imparts it. I heard a friend of Watts say in the Tate Gallery some time ago, when he was taking a little party through the famous chamber: “Every time I try to explain these pictures I see more to explain!” In the act of stating a principle the light brightens for ourselves. . . . While we declare the grace of redemption, grace more abounds toward us. While we testify as to the way of peace we are led into the more secret place. If we would be fine learners we must be ready teachers. Are you saying you cannot be? Is there anything you know about the Lord? Tell the little you know, and the little will grow. Have you no sick neighbor, no care-worn friend, no depressed fellow-pilgrim who is fainting on life’s way? Teach him the little you know. You will be perfectly amazed at the effect upon your friend, but still more wonderful will be the effect upon yourself. As you go home from that house, the truth which hitherto shone like a candle, will burn like a star. “He that doeth the least of these commandments, and shall teach men so, the same shall be called great.” These are some of the secrets of successful discipleship in the school of Christ.
original emphasis, J. H. Jowett, from sermon titled “The School of Christ” in “The Silver Lining”
From experience I know the truth of this quote.