Read the excerpt from "An Image of Africa: Racism in Conrad’s Heart of Darkness” by Chinua Achebe. Travelers with closed minds can tell us little except about themselves. But even those not blinkered, like Conrad, with xenophobia, can be astonishingly blind. Let me digress a little here. One of the greatest and most intrepid travellers of all time, Marco Polo, journeyed to the Far East from the Mediterranean in the thirteenth century and spent twenty years in the court of Kublai Khan in China. On his return to Venice he set down in his book entitled Description of the World his impressions of the peoples and places and customs he had seen. But there were at least two extraordinary omissions in his account. He said nothing about the art of printing, unknown as yet in Europe but in full flower in China. He either did not notice it at all or, if he did, failed to see what use Europe could possibly have for it. Whatever the reason, Europe had to wait another hundred years for Gutenberg. But even more spectacular was Marco Polo's omission of any reference to the Great Wall of China, nearly four thousand miles long and already more than one thousand years old at the time of his visit. Again, he may not have seen it; but the Great Wall of China is the only structure built by man which is visible from the moon! Indeed, travellers can be blind.

What is Achebe’s purpose for writing this passage?

to explain that people with closed minds may not notice wonderful things around them, and their description of a situation may not include everything
to explain the significance of Marco Polo’s journeys in our culture’s growth and to highlight the most important lessons he taught about the places and customs he saw
to explain that people who read a text with a closed mind will likely miss important details and come away with an incomplete perspective
to explain the significance of the Great Wall of China and the damage caused by ignoring it when describing a culture’s growth and development over time