In his chapter “The sympathetic and related systems of nerves” in Schäfer's Textbook of Physiology (1900) Langley defined for the first time the idea that the gastrointestinal tract has a nervous system of its own. He called this system the enteric nervous system (Langley 1900). He repeated this idea in his short monograph in 1921 where he clearly described the division of the autonomic nervous system into three parts: sympathetic, parasympathetic and enteric nervous system. This classification is still used today (Langley 1921). The existence of the plexuses of Auerbach (plexus myentericus) and Meissner (plexus submucosus) has been known since the second half of the nineteenth century. Langley recognized that this system can act to a large extent independently of the central nervous system. He separated the myenteric and submucosal ganglia from the sympathetic (and parasympathetic) nervous system and classified them as a third autonomic nervous system for the following reasons: (1) they have a distinct histology compared to the histology of the paravertebral and prevertebral sympathetic ganglia; (2) it was unclear at that time whether they are connected with the central nervous system by sympathetic and parasympathetic neurons and (3) the sympathetic postganglionic fibers either send collaterals to or form synapses with the neurons of the enteric nervous system (Langley 1900). Up to about 1970 rather little or no attention was given to the enteric nervous system of the gastrointestinal tract; in fact this system was practically ignored.