. It’s not that I find the process of writing hugely enjoyable. There’s a lot of hard slog and long hours involved, and at times I’d almost rather doing anything else. Ultimately, though, it’s rewarding. Anyway, I’ve done it for so long that I would be lost without it. Moreover, I still have things I want to do, and writing has always been for me the best way to wrestle with difficult problems (even if facing a blank computer screen and knowing that no one but you can fill it with words is a daunting one). That others have been interested in what I have written has been an enormous bonus and given me great satisfaction. But explaining complex historical issues for myself has always been the underlying driving-force. 
Ian Machtan considers him not only a thorough historian, but the key individual in unifying the major schools of Hitler scholarship, the Functionalists (also called Structuralists), who saw him as motivated by the exercise of power regardless of purpose, while the Intentionalists focused on his specific vision. 
When interviewed by his publisher, he said he did think he understood Hitler, responding to a question of "If you could meet Hitler, what would you say to him?" with "Please be brief, I have to leave in 2 minutes". His opinion of the two volumes of Mein Kampf? "Doorstops."