If we look in James chapter 3, we will see that a small thing has an influence and controls big things. The small thing dominates over the big things, that is why our tongue can influence or put on fire our whole life.
Sometimes, we think, that it is the big things in our life, which cause big negative effects, but not according to what James chapter 3 is saying.
If we control the small thing-tongue-according to God’s will, we can control our whole life according to God’s will. That is why in James chapter three it says that horses can be controlled with a bridle and a big ship, can be steered to where we want, by the rudder.