A traveller passes a post office and the official rushes him and forces him to take a letter to the next post office.  It is a letter from the king and everything must be done to ensure that it reaches its destination. This is the word in our text for being forcibly enlisted by an authorised official. He does not care whether the traveller wants to or not, nor whether his schedule allows it. The best interests of the mission oblige him. The official has a mission to perform and has full authority. The traveller who knows the law does not argue! He will make the necessary journey so that the king's mail is delivered to its addressee