Timothy Snyder is the author of "On Tyranny: Twenty Lessons from the Twentieth Century" and the Levin professor of history at Yale University. Snyder explains how comparing Trump to Hitler can be useful despite the differences. Following is a transcript of the video.

TIMOTHY SNYDER: So the way to start the discussion about comparisons is to point out that Americans are extremely lazy about history. I mean that's one way in which were definitely number one among major nations. And one of the ways we’re lazy about history is that as soon as anyone suggests that the past might be useful, then we say “but wait it's not exactly the same and therefore I'm just going to discard it.” In that way in two or three seconds we give ourselves an excuse not to think about history. The premise of the book "On Tyranny" is not that Hitler is just like Trump or Trump is just like Hitler. The premise is that democratic republics usually fail and it's useful for us to see how they fail. One of the ways a democratic republic can fail is Germany in 1933. There are plenty of other examples in the book, also from the left wing Czechoslovakia in 1948 becoming communist. The point of the book is that these things really happened over and over again and that intelligent people, no less intelligent than us, experienced them and left a record for us to learn from. So what I'm trying to do in the book is to help us to learn from that record so we don't have events like Germany in 1933 or Czechoslovakia in 1948. Just saying “Hitler's not like Trump" or "Trump is not like Hitler” isn't going to save us. Learning for the past though, could.