"Mind over matter" is an English saying meaning that we can control our bodies with our minds. Now scientists are finding increasing evidence that our mind can have a great effect on our physical health. Since our mind influences how we feel, it's not true to say if someone is ill just because he feels ill. The influence of the mind on how well we feel is the basis of what is known as the placebo effect. A placebo (which is Latin for "I shall please") is a harmless, inactive substance. Patients are sometimes given placebo pills and begin to feel better because they believe that they have been given real drugs and expect to respond to them. The placebo effect is very strong: research on pain suggests that up to 30% of the effect of most painkillers is a placebo effect. So if it is so powerful, why don't doctors use it today? According to Dr Persaud, they really do. "All these things like seeing a doctor, going to a hospital, and being scanned  have a very strong placebo effect," he says. According to the passage, placebos .
may make patients feel worse are not effective pills are not real drugs can relieve all kinds of pains