Optimistic people play a disproportionate role in shaping our lives. Their decisions make a difference; they are inventors, entrepreneurs, political and military leaders - not average people. They got to where they are by seeking challenges and taking risks.

There's a tendency to look at investments in isolation. Investors focus on the risk of individual securities.

People's mood is really determined primarily by their genetic make-up and personality, and in the second place by their immediate context, and only in the third and fourth place by worries and concerns and other things like that.

We don't see very far in the future, we are very focused on one idea at a time, one problem at a time, and all these are incompatible with rationality as economic theory assumes it.

A person who has not made peace with his losses is likely to accept gambles that would be unacceptable to him otherwise.

A general limitation of the human mind is its imperfect ability to reconstruct past states of knowledge, or beliefs that have changed. Once you adopt a new view of the world (or any part of it), you immediately lose much of your ability to recall what you used to believe before your mind changed.

Employers who violate rules of fairness are punished by reduced productivity, and merchants who follow unfair pricing policies can expect to lose sales.