A female sociologist on an African jungle expedition came across a group of tribe children playing around. She wanted to take pictures of them as a record of a scene of the life of the primitive people. No sooner had she held up her camera than the children began to yell in protest.
That reminded her that certain tribes believed a person lost his soul if his picture was taken. She realized that she was just witnessing it: the children were protesting that she should stop robbing them of their souls. So, she apologized to the tribe chief for her insensitivity, and enthusiastically explained that operating a camera has nothing to do with stealing a soul. Several times the chief tried to get a word in, but she didn’t give him time to speak.
Convinced that she had fully reassured the chief, she allowed him to speak. She heard the chief say that the children were only trying to tell her that she had forgotten to take the lens cap off.
The sociologist was prejudiced that the primitive people were ignorant of the mechanism of cameras, and made effort to explain it to the chief, who she expected would relay his understanding to the children. But the children, as well as the chief, had enough knowledge that a camera doesn’t work with the lens cap on, and were telling her to correct her careless mistake.