Fry and Laurie's amazing parody may have its origin in something else amazing: Playing Shakespeare. The four-disc set contains some of the most astonishing Shakespearean actors of the age talking about how best to act.
Here's a short clip. In it, Ian McKellen is asked to enact the first line of The Merchant of Venice with several different shades of emotion and subtext.
It's one line, but its delivery can be so extraordinarily telling. Fry and Laurie have fun with it by imagining an acting coach concentrating all that energy on one word. They make it ridiculous—but there's still some truth behind their ridicule. Not every word in Shakespeare can bear such a multiplicity of interpretation. But many—and perhaps most—of them can.
Links: The Film at IMDB.