Timing is everything. After a nine-month pause, the Federal Reserve decided on Wednesday that the time was right to resume cutting interest rates.

The stock market has been eagerly anticipating the Federal Reserve’s rate action, and for good reason. History suggests that what the Fed has just done will be auspicious for stocks.

There are some important caveats, of course.

For one thing, President Trump and his relentless pressure on the Fed may really make this time different. The presence on the Fed board of governors of Stephen Miran, a top Trump economic adviser on temporary leave from the White House, is a remarkable development. On its face, it detracts from the Fed’s ability to make monetary policy without interference from the president, who is pressing for deeper rate cuts.

Mr. Trump is still pushing to remove Lisa Cook, another Fed governor, in a nasty legal dispute, and his criticism of Jerome H. Powell, the Fed chair, continues unabated. Unquestionably, Fed independence is under daily threat. The markets have responded calmly so far, perhaps because the central bank has been steadfast in upholding its traditional autonomy and in following long-established procedures with prudence. Mr. Powell said on Wednesday that the Fed was monitoring the data as usual and responding to indications that a weakening labor market posed a bigger risk to the economy than rising inflation did. So it was time for the Fed to cut.

But the president has managed to put a cloud over the Fed’s capacity to make difficult choices aimed at ensuring both full employment and low inflation.

All that said, the central bank’s current interest-rate moves generally conform to an encouraging pattern.