Fortune’s Most Powerful Women summit got under way in Laguna Niguel, Calif., last night with Alphabet CFO Ruth Porat doing the opening interview. Porat was at Morgan Stanley before Google, and advised the U.S. Treasury during the financial crisis. Asked what she learned from that experience, she gave three key lessons:

  1. “The most important lesson was you need to identify your source of vulnerability and protect against it early.” For banks, the problem was liquidity; but the lesson can be generalized. Identify your vulnerability, and defend against it.
  2. “The problem for AIG was its derivatives business In London,” which it didn’t understand. “You wouldn’t drive a car with mud on the windshield.” Good data and data analytics are critical to good governance.
  3. “You have to have the will and the means. All too often, when you have the will you no longer have the means.” In short, take the tough decisions early, because it is going to be much harder if you wait until a crisis.

Porat attributes her success at Alphabet to a simple CFO credo: “Anchor everything in data, and great decisions will follow.” Good advice.

Among the 450 women in last night’s audience, was one very noticeable man–Goldman Sach’s brand new CEO David Solomon, who chose to spend his first day on the job with this inspiring group of women.