The driver of a car must give all his attention to his driving. If you are a
passenger don’t take his mind off what he is doing by talking about something
else. And don’t be a ‘back-seat driver’ by telling him what to do and what not
to do.

By extension this proverb means that we should never interfere with a person
who is responsible for the safety of others. Our advice, however well-meant,
may cause an accident.

##### See also:

* If two men ride on a horse, one must ride behind