Lennon 's inspiration for the song came when his son , Julian , showed him a nursery school drawing he called `` Lucy - in the Sky with Diamonds '' , depicting his classmate , Lucy O'Donnell ( later Lucy Vodden ) , who died in 2009 .
According to the Beatles , Lennon 's son , Julian Lennon showed his father a nursery school drawing he called Lucy - in the sky with diamonds , depicting his classmate , Lucy O'Donnell .