POLICE and residents (居民) of Braunschweig in Germany are hunting for the person behind a series of incidents – so they can thank him or her. Soup kitchens (为穷人免费或低价提供食物之处), disabled children, a museum and a man who suffered a burglary (盗窃) have all found envelopes in their mailboxes and put under their doormats (门垫). All of the envelopes contained cash; no one has any idea who they are from.