Failure to prevent / Nicht verhindern

This happily-painted house seems to thumb its nose at the austere new police station opposite.

The banner says “An allem Unfug sind nicht nur die schuld, die ihn tun, sondern auch die, die ihn nicht verhindern”. This translates as something like “Bad things are not only the fault of those who do them, but also those who fail to prevent them“. It was penned by East German writer Erich Kästner in 1933 - the year the National Socialists came to power.

I like the rather pithier English version, attributed to Edmund Burke over two hundred years earlier: “The only thing necessary for the triumph of evil is for (enough) good men to do nothing”.