Invention (and knowledge) is always done on previous, existing work. No matter how smart and what angle would try, a person from roman empire would not be able to invent a gun, or cars or electronics. An invention to happen needs prerequisite knowledge to be commonly available. The person doing the invention doesn't really matter so much. This is why some invention (and facts) were independently created at about the same time, the inventors were not aware of the other guy doing the same thing.<br><br>Technology as progresses and changes loses some aspects when they are not needed at that point in time, e.g. building egyptian pyramids and now we wonder how they managed that.