We’ve studied the two pictures of the tree and the spring. These two pictures are parallel but not identical. The two trees represent two natures. The corrupt tree is the old man or the old person. The good tree is the new man in Jesus Christ. The old man cannot bring forth good fruit. Jesus said that clearly many times. Out of that old, carnal nature will always come fruit that corresponds to that nature.
The fountain, or the spring, represents something spiritual. A pure spring is the Holy Spirit. A corrupt, brackish, salty, impure spring is another spirit.
Therefore, we have two potential problems indicated by the mouth: first, the old, corrupt nature which has not been changed goes on producing corrupt fruit; and second, some kind of spirit, which is not the Holy Spirit, brings forth impure, brackish water. The essence of the teaching is the same in both: that which is inside us, the condition of our hearts, determines what comes out of our mouths.
So the problem of the tongue takes us back inevitably to the problem of the heart.
We are confronted by the truth that Solomon spoke in Proverbs 4:23:
“Above all else, guard your heart, for it is the wellspring of life.” (NIV)
The word "wellspring" agrees with the picture that James used of a fountain or a spring that brings forth the kind of water that is characteristic of that spring.
Another translation of Proverbs 4:23 says:
“Watch over your heart with all diligence, for from it flow the springs of life.” (NAS)
Whatever flows out in your life or through your mouth originates in your heart. If the source is pure, that which comes out will be pure. If the source is corrupt, that which comes out will be corrupt.
Dear Lord, I thank and praise You for the wellspring of the Holy Spirit in my inner being. Thank You that my old nature has died with You on the Cross. I pray that You would help me to guard my heart and not to let the old nature have its way again. I pray that the living water of the Holy Spirit may flow from me more and more, to be a blessing for many. In Jesus' Name, Amen.