One hundred years ago - in 1899 - Emil Kraepelin, Professor of Psychiatry in Heidelberg and later in Munich - created, in two very important pieces of work, the concept of "manisch-depressives Irresein" ("manic-depressive insanity"). The first was entitled Die klinische Stellung der Melancholie(The Clinical Position of Melancholia), and the second publication was the sixth edition of his textbook. In the same year Kraepelin's pupil and colleague, Wilhelm Weygandt, published his book Uber die Mischzustande des Manisch- Depressiven Irreseins (On the Mixed States of Manic-Depressive Insanity). A...