any strong emotion produces certain changes inside the body. for example, when a person is frightened or angry, his heart beats faster and the activity of his stomach stops. if he is frequently frightened or angry these changes will be taking place all the time. if this goes on for long, his health will be affected. he will begin to suffer from tiredness, stomach trouble, sleeplessness and loss of weight. these changes are sometime described as “suffering from his nerves”。 actually, it is not his nerves that are responsible for his suffering, but his emotion.
people often speak of the need of control emotions. and intelligent man will constantly monitor（监视）his emotions. it is true that emotions can surge(汹涌) up so quickly that you may do something on the spur of the moment you will