Abraham Lincoln (Credit: Wikimedia) How will Donald Trump observe Presidents Day? Will he have the inclination or take the time to read about or reflect on the qualities of our greatest leaders? Given how busy Trump is issuing executive orders, fighting with the judiciary, managing the scandal surrounding the dismissal of his national security advisor, becoming acquainted with world leaders and tweeting, the answer is probably no. As a historian who has studied presidential leadership for decades, perhaps I can save him some time by suggesting a few things he might learn from the first Republican president, Abraham Lincoln. Lesson 1: Grow a thick skin Lincoln was more reviled than any American president.