These verses talk about a bit, rudder (helm), a forest fire, a poisonous animal, a fountain, and a fig tree. The first two, the bit and the rudder, are small things but are great in their ability to control a horse or a ship. So it is with the tongue, it is a small thing but wields great ability. A person who can control the tongue shows that he can control his whole body. (James 3:3) For instance, the person who makes an unguarded remark could find himself in a quarrel. Or even worse, the careless remark may force the person to defend or protect himself. Sin is the force to reckon with when it comes to the tongue. Colossians 3:8-9 speaks of the sins that come from the mouth.
The tongue can be as deadly as any fire or poisonous animal. A small spark can start a fire that destroys everything in its' path. The same with a poisonous animal, it seeks to kill and destroy its' prey. Words that proceed from the mouth can cause the fires of hell to rise up and cause strife and devastation. Proverbs 26:20-21 compares lack of fuel for fires to the absence of talebearers and how a contentious man kindles strife. Animals can be tamed but the tongue cannot be tamed. (James 3:7-8) Only God can tame it.
It is not possible to bless God and curse men just as it isn't possible for a fountain to give both sweet and bitter water or for a fig tree to produce olives. That's just not the way it works in this world. The same should be true for the tongue. How is it that the tongue that praises (blesses) also dooms (curses)? It shouldn't be this way. Blessing God and cursing man is contrary to the way things are supposed to be. If the words that are spoken are to bring blessings, each day should begin with a prayer to God. "Set a watch, O Lord, before my mouth; keep the door of my lips. Incline not my heart to any evil thing, to practice wicked works with men that work iniquity:" (Psalms 141:3-4)