Richard Cohen, Opinion writer: Whether he knows it or not, the specter of Lyndon Baines Johnson haunts Donald John Trump. There are some jarring similarities — two big, fleshy men given to vulgarities and gauche behavior, boastful, thin-skinned, politically amoral, vengeful, unforgiving and, most important, considered illegitimate presidents. For Johnson, that took some time to sink in; Trump is already there. This comparison of Donald Trump with Lyndon Johnson gives a balanced comparison between a Democrat and Republican. A comparison of Trump's policies and actions towards people with those of Adolph Hitler's in the 1930s is also possible. Unfortunate for America. Unfortunate for the world.