There is a psychiatrist in New York who has practiced medicine for many years and made outstanding achievements. When he was about to retire, he wrote a monograph on treating various mental illnesses. The book is 1,000 pages long and contains descriptions of various conditions and their treatments. Once, he was invited to give a lecture at a university. During the class, he took out this thick book and said: "This book has 1,000 pages. It contains 3,000 treatment methods and 10,000 types of drugs, but all the contents only have a few words."
