Final answer:
Achebe's purpose for writing this passage is to explain that people who read a text with a closed mind will likely miss important details and come away with an incomplete perspective.
Step-by-step explanation:
He uses the example of Marco Polo's omission of the art of printing in his account of his travels to illustrate how someone can overlook significant information. Achebe emphasizes the importance of keeping an open mind and being aware of one's own biases in order to gain a more comprehensive understanding of different cultures and perspectives. Achebe's purpose for writing this passage is to explain that people who read a text with a closed mind will likely miss important details and come away with an incomplete perspective.