The best designs are those that solve problems without creating new ones.

Trend-following is not such a good model. It’s simply eroded. Things change and being able to adjust is what made Mr. Simons so successful. “Statistic predictor signals erode over the next several years； it can be five years or 10 years. You have to keep coming up with new things because the market is against us. If you don’t keep getting better， you’re going to do worse.

Sometimes you just have to take a leap of faith and believe in yourself.

In the short run, the market is a voting machine but in the long run, it is a weighing machine.