Governor Romney’s victory this evening in the first of the presidential debates — that seems to be the consensus of even the pro-Obama commentators — reminds us of an encounter with Prime Minister Thatcher. This was in the mid- late-1980s, when an editorial writer of the Wall Street Journal, Peter Keresztes, encountered the prime minister at a cocktail reception at London. Mr. Keresztes approached the Iron Lady and introduced himself. As soon as the premier heard the words “Wall Street Journal editorial page,” she leaned into the conversation, shook her finger at him and said, “Stop using the words ‘supply-side.’ Stop using them. People don’t like it. They don’t like it.” There was something about the way the Reaganites talked about the importance of reducing top-marginal tax rates that — even though she agreed with the policy — rubbed her the wrong way.

Watching the debate this evening we couldn’t help but sense that Governor Romney was channeling this sentiment. He just didn’t want to go anywhere near the idea of cutting tax rates on the top margin to generate incentives for work and growth and, en passant, more revenues. We watched the debate with a veteran of the Reagan years, and when Mr. Romney started boasting about how he didn’t want a trillion-dollar tax cut and didn’t want to cut taxes for rich people, our colleague stalked out of the room. And yet, there were indications in the debate that Romney understands the principle of dynamism, meaning that tax cuts generate incentives to work, which generates income, which generates growth, which generates more tax revnues. Mr. Romney just didn’t want to talk about it in the classical supply side terms.

Here is the governor. “I will not reduce the taxes paid by high-income Americans. . . . I will not under any circumstances raise taxes on middle-income families. I will lower taxes on middle-income families. . . . But let’s get at the bottom line. That is, I want to bring down rates. I want to bring the rates down, at the same time lower deductions and exemptions and credits and so forth, so we keep getting the revenue we need. And you’d think, well, then why lower the rates? And the reason is because small business pays that individual rate; 54% of America’s workers work in businesses that are taxed not at the corporate tax rate, but at the individual tax rate. And if we lower that rate, they will be able to hire more people. For me, this is about jobs. This is about getting jobs for the American people.”

In other words, Mr. Romney gets it. He understands that his critics are advocates of what we supply-siders like to call “static analysis” and that he is for what we like to call “dynamic analysis.” He understands that if the rates can be brought down, the result will be more employment, more jobs, more taxable income, more growth, more tax revenues. One could call him a secret-supply-sider. We’ve been printing column after column by Lawrence Kudlow, who understands the issue cold and has been marking the importance of the taxes and growth points. Mr. Romney didn’t quite confront things as forthrightly as Mr. Kudlow would have (we haven’t talked with him this evening, but that’s our guess). Or as forthrightly as Mr. Keresztes of the Wall Street Journal did with Mrs. Thatcher in the 1980s.

Mr. Romney did, however, in his own way signal that he understands the supply-side principles and the importance of dynamic analysis. So it’s an encouraging start to the presidential debates. We’d like to think it points Mr. Romney’s running-mate, Congressman Paul Ryan, in the right direction for the next debate, which is the vice-presidential round taking place October 11 at Kentucky. Mr. Romney’s biggest achievement in the debate this evening is that he made this opening. The next opportunity will come when there’s an opening to talk about the collapse of the dollar, which is now worth less than half the amount of gold as when Mr. Obama acceded to the presidency. This is a point on which, we are confident, Mrs. Thatcher, daughter of a grocer, would be less shy — and on which Mr. Romney is in a position to leap ahead of the president in the next presidential round.