From Einbeck, or Einbock it travel to Munich where Monks brewed it in the harvest season (the fall) and drank it during their fasting time. The Monks named the beer Salvator (savior), since it helped them abstain from eating. The original Bock was lower in alcohol content and was a very malty brew.
There is also a story of a drinking contest between a Bavarian duke and a knight form Brunswick. "Each was given a cask of beer from his opponent's store. After a few drinks the knight found himself on the ground while the Bavarian remained in his seat. The embarrassed knight blamed a goat that had found its way into the courtyard. The Bavarian, who also happened to be the brew master, laughed and told the knight, "The Bock that threw you over was brewed by me (source: Bryce Eddings Bock moves to Munich and gets a name)." This seems to be a great tale and it helps that
the word Bock actually means billygoat in German, but my impression is that it is just that, a great tale.
One common myth about Bock beer is that it’s brewed using the leftover malt sludge left at the bottom of the fermenting tanks. According to this myth, Bock was brewed in the spring, and was when they cleaned out the brew tanks, it was assumed that bock was probably brewed with the leftover malt that was present from the previous years’ brewing activities. The brewers did not want to waste the malt so the legend says that they used to to create Bock beer.
Another theory is that it is named after the sign of the Capricorn (the goat), since some say it was brewed under that sign. This theory makes Bock a winter brewed beer.
Today's Bock beer is a bottom fermenting Lager that takes several extra months of lagering (cold storage) to give it a smoother finish. Bock beer today also has a higher alcohol content then when the monks first brewed it way back when.
As you can see the origins of Bock beer are truly unclear. All of these stories place the brewing time at a different time of year.
There seem to be four popular types of Bock beer. Traditional Bock, Maibock, Doppelbock, and Eisbock. Maibock is brewed by taking traditional bock and infusing it with more finishing hops, giving the finished product a little more bitterness and more balance than traditional bock. Doppelbock is a double Bock, and has a higher alcohol content and more intense malty and rich flavors than ordinary bock. Eisbock has the most alcohol content because they freeze Doppelbock and then remove the ice. This creates a beer that has a much higher alcohol content because part of the water has been taken out.
Bock beer is a great seasonal beer. It’s a great beer to drink when you want a sweeter, richer, maltier beer with not much hop at all.