Answer:
Beowulf
Explanation:
The dramatic tradition of English literature saw its beginnings with Anglo-Saxon settlers and their Germanic tradition. Beowulf, an epic poem of the 8th Century, is the most important writing of the time and its language is Anglo-Saxon, commonly known nowadays as Old English. This what makes it very hard to understand for modern English speakers.
It suggests that Groucho believes the writer of the original letter knows as little about the city of Casa- blanca (his history is filled with absurd details) as he knows about how different the Marx Brothers' film A Night in Casablanca would be from the famous Casablanca.