Beginning writers are endlessly encouraged to “write about what you know.” But it’s the task of a biographer or a historian to know what you write about, to get beneath the surface. You have to know enough to know what to leave out. You have to know enough so that as you’re writing, everything is second nature. And you have to know a great deal that you can’t get from books - especially from other people’s books on the same subject, or even from printed records, such as letters, diaries, and contemporary newspaper accounts.
