Depression was thought to be discovered as far back as Ancient Greece. The Ancient Greeks thought that depression was caused because the ‘depressed’ person did not have enough body fluids. Later, in the 11th century, physicians came up with their own ideas about melancholy (depression). They thought that melancholy was a mood disorder. They further believed that this mood disorder could make a person prone to suspicion. These physicians also believe that melancholy (depression) could make someone have phobias.