The question is why one should be so inwardly preoccupied at all. Why not reach out to others in love and solidarity or peer into the natural world for some glimmer of understanding? Why retreat into anxious introspection when, as Emerson might have said, there is a vast world outside to explore? Why spend so much time working on oneself when there is so much real work to be done?

In matters of the heart as well, a certain level of negativity and suspicion is universally recommended. You may try to project a thoroughly positive outlook in order to attract a potential boyfriend, but you are also advised to Google him.

The failure to think positively can weigh on a cancer patient like a second disease.

As a recent editorial in the Journal of Clinical Oncology put it: "What we must first remember is that the immune system is designed to detect foreign invaders, and avoid out own cells. With few exceptions, the immune system does not appear to recognize cancers within an individual as foreign, because they are actually part of the self.

When our children are old enough, and if we can afford to, we send them to college, where ... the point is to acquire the skills not of positive thinking but of critical thinking ...

I realize that after decades of positive thinking the notion of realism, of things as they are, may seem a little quaint. ... When the stakes are high enough and the risks obvious, we still turn to people who can be counted on to understand those risks and prepare for worst-case scenarios. A chief of state does not want to hear a general in the field say that he 'hopes' to win tomorrow's battle or that he's 'visualizing victory' ...

We need to brace ourselves for a struggle against terrifying obstacles...bot h of our own making and imposed by the natural world. And the first step is to recover from the mass delusion that is positive thinking.

There is a vast difference between positive thinking and existential courage.