When we put bits into the mouths of horses to make them obey us, we can turn the whole animal.
Or take ships as an example. Although they are so large and are driven by strong winds, they are steered by a very small rudder wherever the pilot wants to go.
Likewise, the tongue is a small part of the body, but it makes great boasts. Consider what a great forest is set on fire by a small spark.
The tongue also is a fire, a world of evil among the parts of the body. It corrupts the whole body, sets the whole course of one’s life on fire, and is itself set on fire by hell.