Here "fly away" and "be chased away" represent disappearing. They may also imply being forgotten, since dreams and visions disappear when people forget them. Alternate translation: "He will disappear like a dream ... he will be forgotten like a vision of the night" (See: [[rc://en/ta/man/translate/figs-parallelism]] and [[rc://en/ta/man/translate/figs-simile]])