Student or Learner
The police are the public and the public are the police; the police being only members of the public who are paid to give full time attention to duties which are incumbent on every citizen in the interests of community welfare and existence.
what does this quote mean ?
1. the police are members of society
2. the police are paid to enforce the rules of society
3. everyone (every citizen) has a duty (the duty is incumbent) to follow and to enforce societal rules
Community welfare and existence refers to those rules which are needed for the good of sociey and for the fact that society (or a group of people living together) can live together at all (the existence of a society).
In essence, the writer is saying that even though the police are paid to moinitor the society, they are also members of that society and that everyone else has a similar duty.