“When dictators come to power, the first thing they do is take away the people’s weapons. …I do not believe that [our nation’s leaders] have any desire to impose a dictatorship upon us. But this does not mean that such will always be the case. A nation rent internally, as ours has been in recent years, is always ripe for a ‘man on a white horse.’ A deterrent to that man, or to any man seeking unlawful power, is the knowledge that those who oppose him are not helpless.”