>Quote Investigator: The earliest match found by QI appeared in “The Evening Sun” of Baltimore, Maryland in April 1929. The statement occurred in a filler item without attribution. Boldface added to excerpts by QI:
>If he says his gas tank is half-full he’s an optimist. If he says it’s half-empty he’s a pessimist.
> “The glass is half full” and “The glass is half empty” are descriptions of the same phenomenon but have vastly different meanings. Changing a manager’s perception of a glass from half full to half empty opens up big innovation opportunities.