I was just reading some reviews and overviews of the book and walked away with the same impression. The most interesting definition (partly just IMO, but also

I was just reading some reviews and overviews of the book and walked away with the same impression. The most interesting definition (partly just IMO, but also because it's the one whose derivative of 'being talked about' is also large right now), which is also an important concept in certain Eastern philosophies for instance, has to do with a cognitive mode perhaps best characterized by 'openness'—but since that term is fraught, let me try something from scratch. There is something in our brains that works in a very sphincter-like way—similar to the pupil, for example. Rather than letting in more or less light, however, it determines how much you will be affected by present percepts. If it is closed, you can see all sorts of horrendous or magnificent stuff and have little to no reaction; if wide open, you may genuinely weep while hearing a beautiful song or something. (I don't want make strong claims on this next point, but I think it's useful to say something on the matter: what determines the openness here has a number of factors, but how safe you feel at the moment [e.g. anxiety can block it] and how 'internally pre-occupied' you are, are probably two big ones.) The empathetic 'cognitive mode' I was describing earlier is essentially just being in the 'open' state. It allows you to be affected by someone else's present suffering in a very direct/immediate way, without contemplation—which is why the author's alternative of 'rational compassion' is so controversial: the claim of modern proponents of the sort of empathy I've been describing stresses the importance of this direct connection and immediacy, claiming that being in this cognitive mode is the only way to genuinely act in the interest of another person—whereas when you approach altruism purely rationally, other motivations will typically be involved. But, the picture I got is that the book doesn't actually talk about that sort of empathy at all.