The human brain has developed over millenia. Like a non-stop power plant, the brain added new structures to basic ones (controlling basic functions like breathing). The crowning achievement is the cortex, the largest brain structure, where higher thought and reasoning take place.
Scientists have learned that sensory input, e.g., sounds, do not have to travel to the cortex to induce fear. Impulses need only travel to a primitive brain structure called the amygdala.
When FDR delivered his first inaugural address, he appealed to reasoning, though his topic was the fear of a nation shattered by the Great Depression. Like dictators and demagogues through history, Donald Trump goes straight for the lower brain with pointed, uncomplicated messages that require little thought. For example, his nicknamesl for nearly all of his opponents (Low Energy Jeb, Little Marco, Crooked Hillary) make for instant recognition and easy identification--and great ratings for cash-starved cable media. Wash, rinse, repeat.
Trump echoes right wing talk radio hosts, who offer short, immediate solutions that fit neatly into a brief format. No exhausting engagement of the thinking brain required. Fear is our most powerful emotion and when Donald Trump boasted he knew how to win this election, like ad men from Madison Avenue, he knew what worked: the low road to the White House. Hillary Clinton and the Democrats have a long, arduous path to the thinking brain to overcome the power of fear and other powerful emotions.