Michael T. Flynn, who briefly served as national security adviser, gave President Trump at least one piece of excellent advice.

According to The Huffington Post, it was 3 a.m. when Mr. Flynn got a call from the president with an important question: Is it good for the economy to have a strong dollar or a weak one?

Mr. Flynn, whose background is in the military rather than in macroeconomics, said he didn’t know. He suggested that the president ask an economist.

Just so.

Judging by those with whom Mr. Trump chooses to surround himself, it seems that the new president is averse to talking with professional economists. But over time, he will probably get around to appointing the three members of his Council of Economic Advisers, as is required by law. (Some reports suggest that the council chairman may be Kevin A. Hassett of the American Enterprise Institute, who would be a fine choice.) Here are a few things that the president could learn from his economists in his first briefing.