During World War II, a volunteer named Dock, who assisted the hospital in the field hospital to help the death and help the wounded, wrote a sentence on the wall in order to drive away the dark clouds in the heart of the wounded and give the wounded the power to overcome the pain: Here it is dead. This sentence has brought countless wounded the power to overcome the pain. After the end of World War II, Dock became a postman. He firmly believed that in addition to bringing mail to people, he could also pass on happiness to people. Therefore, he always took a lot of notes with words of encouragement: "Don't worry, today is a good day", "Smile with a smile", etc. Everywhere he went, people felt happy. Ke was not a performing artist or a writer, but he did what a performing artist and a writer might not necessarily do. What is the main point of this passage? ['Volunteers and artists, writers.', 'Giving someone a rose.', 'Passing happiness.', 'Helping others is a loving dedication.']