What did Astronaut Neil Armstrong mean when he said,.?

What the men of the apollo missions did was imposable at at least that is what the world thought in the 60s this is his reference to truth protective layers and the breakthroughs that he mentions and as for the great ideas undiscovered he means that we should push ourselves to do the imposable again and not just in space exploration but in other fields after all when a new invention comes to light everybody says that will not work.