At first it seems a small joke in reference to Bohr's logorrheaic writings, whose impenetrability became legendary.
He was quite clear about what he wanted to avoid: out-of-date talk and learned impenetrability in general.
Other yeggs scowled at the thought of having to add to their equipmentjimmy, "soup" (nitroglycerin), oxyacetylene blowtorch a gas mask of exceedingly high impenetrability.
Despite cuts, Fort Knox's iconic status endures Few military posts have a place in pop culture as rock solid as Kentucky's Fort Knox, thanks to its mysterious gold vault. The name of the historic base is practically synonymous with impenetrability. ...
June 30, 2013 - Associated Press via Yahoo! News