It is the balancing organ fish have⁠—the air-bladder. Even today we actually still have a few very rare kinds of fish whose air-bladder is at the same time a sort of lung; and on occasion can use it to breathe with. In your dream you made use of your lungs in exactly the same way as these fish do their air-bladder.”

He even brought me a volume on zoölogy, and showed me the original drawings of these ancient fish. And with a peculiar thrill I felt an organ of early evolutionary epochs functioning in me.