6. Keep It Simple, Stupid

Modern finance profits from complexity, because befuddled customers are more profitable ones. But do all those fancy financial instruments actually do the economy any good? Paul A. Volcker, the former Fed chairman, once said the A.T.M. was the only beneficial financial innovation in the recent past. He may have exaggerated, but he had a point. Who needs credit default swaps on collateralized debt obligations, and other such concoctions?

7. Standardize Derivatives and Trade Them on Exchanges

Derivatives acquired a bad name in the crisis. But if they are straightforward, transparent, well collateralized, traded in liquid markets by well-capitalized counterparties and sensibly regulated, derivatives can help investors hedge risks. It is the customized, opaque, “over the counter” derivatives that are the most dangerous — and the ones more likely to serve the interests of the dealers than their customers. Dodd-Frank pushed some derivatives toward greater standardization and transparent trading on exchanges, but not enough. The industry is pushing to keep more derivatives trading out of the sunshine.

8. Keep Things on the Balance Sheet

Before the crisis, some banks took important financial activities off their balance sheets to hide how much leverage they had. But the joke was on them. The crisis revealed that some chief executives were only dimly aware of the off-balance-sheet entities their banks held. These “masters of the universe” hadn’t mastered their own books. Dodd-Frank specifies that “capital requirements shall take into account any off-balance-sheet activities of the company.” That’s a welcome step toward making off-balance-sheet entities safe and rare. Now regulators must make the rule work.

9. Fix Perverse Compensation

Offering traders monumental rewards for success, but a mere slap on the wrist for failure, encourages them to take excessive risks. Chief executives and corporate directors should “claw back” pay when putative gains turn into losses. If they don’t, we may need the heavy hand of government to do it.

10. Watch Out for Consumers

The meek won’t inherit their fair share of the earth if they are constantly being fleeced. What we learned in the crisis is that failure to protect unsophisticated consumers from financial predators can undermine the whole economy. That surprising lesson mustn’t be forgotten. The Consumer Financial Protection Bureau should institutionalize it.

Mark Twain is said to have quipped that while history doesn’t repeat itself, it does rhyme. There will be financial crises in the future, and the next one won’t be a carbon copy of the last. Neither, however, will it be so different that these commandments won’t apply. Financial history does rhyme, but we’re already forgetting the meter.