The vision of the measuring line reveals the condition of Jerusalem which will result from the overthrow of her enemies. The young man with a measuring line goes forth to measure the restored city, and is prevented from doing so by an angel messenger, who, in figurative language, tells him that Jerusalem will be such that it will be impossible to measure.
The nature of that prosperity is indicated in the statement that Jehovah's presence will make walls unnecessary, and its extent be so vast as to make walls impossible. In view of this remarkable vision of ultimate prosperity, the prophet calls the scattered people to return, and tells them to rejoice that Jehovah will dwell in their midst.