'On periodical depressions and their pathogenesis' by Carl Lange (1886).

Carl Lange was the founding father of neurology in Denmark, authoring several pioneering works within this field; however, these remained largely unknown internationally as he did not have them translated into a major language. He became a pioneer of psychophysiology with his contribution to the so-called James-Lange theory of emotion. His treatise on'periodical depressions' ('the Lange theory of depressions', 1886), is not only an early historical landmark but also a masterly 'modern' description concerning the nosology and nosography of recurrent depressions. Moreover, it is a landmark in the early history of lithium therapy, sadly ignored by Lange's contemporaries, but which little more than half a century later, with Cade's rediscovery of lithium's therapeutic effect in mood disorders in 1949, ushered in modern psychopharmacology.