I believe that our society's "mistake-phobia" is crippling, a problem that begins in most elementary schools, where we learn to learn what we are taught rather than to form our own goals and to figure out how to achieve them. We are fed with facts and tested and those who make the fewest mistakes are considered to be the smart ones, so we learn that it is embarrassing to not know and to make mistakes. Our education system spends virtually no time on how to learn from mistakes, yet this is critical to real learning.

Nature gave us pain as a messaging device to tell us that we are approaching, or that we have exceeded, our limits in some way.

Most people have a hard time confronting their weaknesses in a really straightforward, evidence-based way. They also have problems speaking frankly to others. Some people love knowing about their weaknesses and mistakes and those of others because it helps them be so much better, while others can't stand it.

The expression I use: Pain + Reality = Progress. Whenever I would have a painful mistake, I started to view that as puzzles that would give me gems if I could solve the puzzle. So, it made me thoughtful - what should I do differently next time? That was the puzzle. And the gem was some principle for handling the same thing when it came along again, and then I would write it down. And by writing it down and referring to it, and also being able to show it to other people so that we could agree that that was a good way of handling that thing - that was very, very powerful.

When people get at each other's throat, the rich and the poor and the Left and the Right and so on, and you have a basic breakdown, that becomes very threatening.

As Harvard developmental psychologist Robert Kegan, who has studied Bridgewater, says, in most work places everyone is working two jobs. The first is whatever their actual job is; the second consists of managing others' impressions of them, especially by hiding weaknesses and inadequacies - which is an enormous waste of energy.

The biggest mistake investors make is to believe that what happened in the recent past is likely to persist. They assume that something that was a good investment in the recent past is still a good investment. Typically, high past returns simply imply that an asset has become more expensive and is a poorer, not better, investment.