Choline, "The Mother-Substance-of-All"
In 1865, Oscar Liebreich (1839-1908), while researching the human brain as a medical student in Königsberg, Germany identified a substance that he described as "the mother-substance-of-all" and which he called "protagon". The word 'protagon' is the root word of protagonist (from Greek) meaning the 'one that takes the main part'. The substance that Liebreich found in the brain was the first time that the 'substance' of brain was described. It was this fatty material, the components of which he subsequently determined were made out of fatty acids and containing a newly discovered molecule that he called "neurine". It soon became evident that 'neurine' was identical to the molecule that Adolf Strecker had purified from the bile of an ox and called 'choline' (chol=bile in Greek). Neurine and choline were the same molecules and yes, perhaps the 'mother-substance-of all' is a fitting description.
'Protagon' was so named because it was the first definitely identified principle substance of the brain. A protagonist is typically the person who takes the leading role in a drama, enterprise or in this case, the constituent of brain.