I am told this was actually articulated by one of Adolf’s henchmen. The law is about how to convince the public of something that is not true. It goes like this:

Tell a lie. Tell a big lie. Tell it over and over and over. The bigger it is, and the more you tell it, the more people will be convinced that it must be true.

There is a perverse logic to this: something like, he/she wouldn’t say that if it werent’ true, eh?