Know yourself!

Who are you? It’s more important than ever to know the answer to this question.

Think about it - When you’re on shaky ground (aren’t we all these days?), when your bosses and direct reports question your moves (admit it, they do), and when you’re rethinking your life or career (you’d better be, or you’re a fool), you need one core competency: Know thyself.

A primer in this regard: a book that I talk about in Fortune’s current cover story about Meg Whitman, the former eBay (EBAY) boss who’s running to be California’s next governor. The book is Politics Lost by Joe Klein, the well-known columnist at Time. For tips on how to preserve your authentic self - yes, outside politics as well – read Klein’s sidebar offering advice to Whitman.

And take a look back at Postcards over the past week. Last Friday’s was about reinvention – from Cisco (CSCO) to former Starbucks (SBUX) CEO Jim Donald to Procter & Gamble’s (PG) Susan Arnold, who just walked away from her job as president there. This week, we featured an amazing woman, Jacqueline Novogratz, who talks about her transformation from banker to venture philanthropist. And yesterday, we posted an exclusive on Dawn Hudson, the former CEO of Pepsi-Cola North America (PEP), who called me on Wednesday to say she’s ready to “reinvent” after 14 months on the sidelines. She landed a new job at last. But not the high-powered gig you would expect of her.

Face it, the only sure way to stay sane and be happy in this uncertain world is to get to know our true selves…and if needed, change to like that true self. Enough psychotherapy. Have a good weekend!

P.S. I’m in Hartford, Conn. today visiting folks at The Hartford, the insurance giant. Ramani Ayer, The Hartford’s chairman and CEO, just asked me,”What do you think are the traits of the best leaders?” I gave him my list of five traits, then he gave me his. No. 1 on his list: self-awareness. What traits do you think the best leaders have?