Now's the time when Wall Street's biggest lie about trading can backfire

Right now, markets are in complete and utter terror mode. The UK's vote to leave the EU has screens across Wall Street awash in red. No one knows when it will end.
And so now is a good time to talk about one of the biggest lies on Wall Street — a lie traders are told from their first day on the desk.
The lie is simple: Do not trade with emotion.
The Wall Street trader, at least in Wall Street's imagination, is a cowboy swaggering with silent confidence. Knowledge and logic are their guides