[1] After a brief history on the many different forms of manly arts through the years, from early man bashing each other with their primitive weapons (and kicks), to Egyptians poking at their opponents' eyes, to the Medieval Era where knights in armor hammer each other with maces, to the romantic age where chivalrous gentlemen are slapping each other with the glove, and then to early fisticuff brawling (with the lack of proper science when men are fighting as long as 75 to 80 rounds), Goofy demonstrates the different methods of boxing.
The narrator shows the audience, with Goofy as the model, learn about proper breathing exercises, skipping rope for conditioning, as well as punching the bag to measure coordination, agility, and developing the skill of "covering up", and shadow boxing literally against his shadow, normally used for perfecting form and timing.
The shadow makes his appearance as the narrator explain about good sportsmanship when both fighters give a friendly handshake before they pit their skills.
With the motion of the slow-motion camera, Goofy is trying to deliver the uppercut against the shadow, much like a ballet dancer, but the opponent countered the blow and sends the Goof flying across the hall.
Of course, there are rules involving fouls when the shadow hits Goofy below the belt, something that every fighter in boxing should never do, because it is very unsportsmanlike, unethical, unnecessary, and uncomfortable.