That clowns have a scary edge to them is well known. The observation, however, is less frequently made of comics, where it is equally true. The best comics inspire laughter that draws upon delight but also fear. (Think of how Shakespeare's fools not only entertain but deliver frightening truths.) One of Richard Pryor's most famous routines was a reenactment of a heart attack.
This all points back to the principle of Opposites, one of twelve 'guideposts for actors' identified by Michael Shurtleff in his book, Audition. Harpo Marx's performances routinely bring together opposites—joy and anger, libidinal aggression and prepubescent innocence, and more.
One particularly striking set of opposites in his work is that between slapstick and the sublime, especially evident when he pauses to play a harp solo.
Note how these instantaneous shifts in and out the sublime do not negate the slapstick that precedes it. To the contrary, these moments deepen both the slapstick and the entire performance.
The sublime is a crucial element of the Marx Brothers' humor at large. Without it, Groucho's wagging eyebrows are merely waggish.
Thank you for reading.