Louis Brandeis started off by embracing the Theodore Roosevelt notion that hyphenated Americanism was unpatriotic. You couldn't have dual loyalties. But then he thinks and he reads and he becomes the head of the American Zionist movement after having previously been a secular Jew in this amazing intellectual evolution.

Whenever I felt tempted to, I don’t know, watch cat videos or bad Netflix TV instead of writing this Brandeis biography, I thought of his stern but kindly visage and buckled down and wrote the damn thing, because there’s so much information out there, and these are such anxious times in democracy, such unreasonable times.

[Louis Brandeis] at the age of 57 decided to become the head of the American Zionist movement was more influential than anyone else in the 20th century in persuading Woodrow Wilson to recognize a Jewish homeland in Palestine.

The tyranny of Harvard and Yale is another thing that transcends this problem of the set point. But what's so striking about [Louis] Brandeis is he had this vision of cultural pluralism that completely gave the lie to the idea that there was any inconsistency between being Jewish or being a woman or being African American and being fully American.

When I was in law school I was taught that the great writers were people like [Oliver Wendell] Holmes Jr. and [Benjamin N.] Cardozo. But you go back and read their prose and it's sort of perfumed and very ornate and show-offy. And they're constantly striving for these abstractions that seem archaic nowadays.

And he [Louis Brandeis] talks to his young acolyte, Horace Kallen, who wrote this beautiful book called Cultural Pluralism, and he comes to believe that by being better Jews, or better members of our ethnic group, we can be better Americans, because America is like an orchestra in which identity is defined by the diversity of perspectives that we bring to the table.

For [Louis] Brandeis, you know, ethnicity and background are much less important than facts and reason. And he believes that far from wanting to efface our diversity of perspectives, we have to embrace it because that makes us more American, not less. In that sense, he's incredibly modern in an age of cultural pluralism. And it is disappointing for just the reasons you say that not everyone has embraced his pluralistic vision.