For better and worse, he is a more solemn figure now. His voice is thin and clotted, and his gestures have slowed, but, in our conversation, his mind seemed unchanged. He never bungled a name or a date. At one point, he pulled out a white notecard inscribed with some of Trump’s most alarming comments: his threat to terminate the Constitution, his casual talk of being a dictator on “Day One,” his description of immigrants as “poisoning the blood of our country.” Biden tossed the list on his desk and gave a look of disbelief. “What the hell! ” he said. “If you and I had sat down ten years ago and I said a President is going to say those things, you would have looked at me like, ‘Biden, you’ve lost your senses.’ ”