Can you interpret these sentences. Benedetti induced pain in human volunteers by inflating a blood pressure cuff on the forearm. He did this several times a day for several days, using morphine each time to control the pain. On the final day, without saying anything, he replaced the morphine with a saline solution. This still relieved the subjects' pain: a placebo effect. But when he added naloxone to the saline, the pain relief disappeared, Here was direct proof that placebo analgesia is mediated, at least in part, by these natural opiates. Still, no one knows how belief triggers endorphin release, or why most people can't achieve placebo pain relief simply by willing it. Would you explain this paragraph after the two sentences what is the main idea would you simply make it clear for me to get the idea .thanks a lot for your time