He extrapolates from this insight to say that the ability to speak (and write!) clearly is essential to leadership (be it political, scientific, or some other kind) in a liberal democracy.
This is an obvious point but Gopnik makes it really well, and it gave me a new perspective on Lincoln's political brilliance; in the Lincoln essays, Gopnik focuses on his frequent use of one and two syllable words.
402. Does Obama use many one and two syllable words? I'm going to try to listen during his upcoming speeches to see often he uses straightforward vocabulary.
In one of the essays, Gopnik talks about Darwin's excellent use of "sympathetic summary." By this term, he means summarizing the arguments against your own in the most sympathetic (strong) way possible. Darwin did it particularly well in setting up the arguments for (1) irreducible complexity and (2) the lack of intermediate species.
I loved Gopnik's discussion of sympathetic summary. This is a writing skill that I tried to teach - I think that the best non-fiction writers excel at vividly establishing the counterpoints to their arguments/theses and then -- after establishing them -- showing their weaknesses.
A couple of other key points:
1. Gopnik writes that Lincoln loved Shakespeare - in particular, Macbeth and the character of Claudius in Hamlet. As I understood Gopnik, Lincoln thought that Shakespeare explored the theme of ambition particularly well.
2. In terms of spirituality, Gopnik argues that Lincoln was a stoic. He seemed reluctant to say that Lincoln did not believe in God, but he was clear that Lincoln did not adhere to any particular dogma. The "ages versus angels" reference is resolved to some extent by Lincoln's finding God in history and the horizontal connection of people to their predecessors and their successors.