Respuesta :
4. He had come to understand...that bodily functions are affected by spiritual and emotional phenomena as well as by physical influences.
This is the main idea because the reason why he was examining the patient's life instead of his body and why his colleagues thought he was crazy was because of this idea that a person's spiritual and emotional well-being also affected his/her physical health. This is all summarized in sentence 4 so it is the best option.
The correct answer is number four. The main idea is supposed to be the most important thought from the piece of text, in other words, what the whole text should talk about.
In this case, the first paragraph talks about the background of the information, the second paragraph talks about the environment he was making assumptions in and the third one is just a perception of people surrounding him, however in the fourth paragraph, he makes the statement of what the whole text will be about, therefore, number four is the correct answer.