It seems that one of the most popular and frequently chosen icons of good, German brewing is a happy monk. On a quest to learn as much as I can about the many, many different German beers available while living in Germany, I have noticed that the image of a friendly, smiling monk — usually hoisting aloft some type of beer-filled container — adorns a surprisingly large percentage of the German beer labels I have seen while wandering through numerous German Getränkemärkte (beverage markets). A little bit of Internet research helped me gain an understanding of why Germans often equate monks with good beer.
According to the Drunken History web site, the earliest beer brewing in Europe was done in individual homes, which allowed for a huge variance in the style and quality of home brews. Monasteries started brewing as a way to pay taxes, remain self-sufficient and serve their communities. Monks dedicated time and effort to learn how to brew and were able to significantly increase the quality of beer. Monasteries across Europe were supplying good beer to their communities during the middle ages and beyond.
That long history and reputation of monks as brewers of good beer has definitely contributed to the iconography used on many German beer labels. Below is a gallery with scans of the beer labels I have collected that feature monks.