The main objective of the commissioner is to get the foreigners to stop selling opium to the Chinese. We learn this in the passage. The commissioner begins by explaining what the punishment is for Chinese people who find themselves involved in the opium trade. However, he then states that he believes foreigners are as much to blame for the trade, because they are the ones bringing it into the country. The commissioner wants the foreigners to reflect on this and change their ways, or face the legal consequences.