I agree quite a bit with > I think "psychological resilience" means essentially the brain's ability to maintain its own internal state independent of reality -

I agree quite a bit with > I think "psychological resilience" means essentially the brain's ability to maintain its own internal state independent of reality -- in more practical terms, the brain can remain confident of its own ability to operate in reality, even as reality throws curveballs and does all kinds of wacky stuff In particular, I think one of the big differences between depressive people and non-depressive people is whether their upbringing/community/learned value system is one that is "sturdy" ie resilient to damage. A socially vulnerable person who has never had a strong foundation for their social legitimacy goes into every social interaction looking for evidence of being accepted. A person who has grown up with their acceptance never in doubt doesn't need anything from each new interaction. So the former person is susceptible to trauma from every interaction, whereas it would take the latter person a long time be worn down by negative responses to the point where it would affect them psychologically. I suspect that the mechanism by which modern life causes such an epidemic of depression is that people grow up less integrated into communities and family units that provide this stability-of-identity by the time they get to adulthood. If you reach adolescence with no model of what a legitimate person looks like or how to be one, it makes sense that you will flounder, and being a social being that craves acceptance by society, you can end up obsessively trying to find that legitimacy in every interaction. (Another mechanism for this is when someone grows up with an abusive or otherwise psychologically damaging home life, such as never being validated by their parents and always criticized -- so even if they are by all metrics very good at life or very good at socializing, they're programmed to never perceive themselves as good enough, so they never get to that state of imperviousness to slightly-negative reality.)