Tongue is like …

The tongue is like a rudder - The rudder is very small, but it helps steer a large ship.

The tongue is like a rein - The rein in the mouth of a horse is small, but it helps control this big animal.

The tongue is like a fire - If out of control, fire can make a lot of damage, but when controlled, fire is a blessing.

The tongue is like an animal - An animal, for example a horse, is a blessing for a household, but if it is wild and unruly, it can cause a lot of damage.

The tongue is like a spring - A spring cannot give fresh water one day and salt water the next.

The tongue is like a fruit tree - The vine cannot produce grapes one day and figs the next.