You feel that you should be boning up on The Sources of Normativity, oh you poor thing. What the hell is Normativity? There is such thing as normatively and normativeness, but normativity, surely, is one of those inventions by scholars that should make all people with any sense of normativeness run and run and run. I have, in my household, only to bone up on bands whose names are too long and non sequitur-esque to remember, youths who can't sing or play instruments but are filled with exuberant rage.
As for Simon Schama, I have not read The Embarrassment of Riches, but do remind me what it means exactly to be good. Snape, perhaps as you say, is good after all. If there is such leeway perhaps it is not so difficult to be pretty good. Will pretty good do?
And as for the young women reviewers in the Times, I have always felt that no writer should review another, which, in that unlikely unevent, would mean that hundreds of reasonable and extremely well-read critics must be found, essayists who have absolutely no axe to grind, do not have to be polite, but of course would be failingly so unless a book was thoroughly terrible and he could not help himself. Although I would miss Lorrie Moore's gorgeously witty and smart reviews.