It was quite clear that Hillary Clinton won Monday night’s presidential debate.

I’m sure many tuned into the debate to watch Donald J. Trump’s antics, and his campaign has been thriving on his unpredictable and outrageous behavior, but the most obvious thing to emerge from Monday was a clear sign (if it was not already clear enough) that Mr. Trump is not fit by any means to be the leader of this country.

Mr. Trump tried to justify the fact that he has never released his tax returns, he advocated for the controversial police tactic of “stop-and-frisk,” which gives police officers the right to stop and frisk anybody they deem suspicious (and which has been ruled unconstitutional in federal court), and when asked about his part in the “birther” movement concerning President Obama, he claimed that Mrs. Clinton’s campaign started the whole thing, which is an outright lie.

When asked why he continued to press the matter years after Mr. Obama’s birth certificate was officially released, he responded: “But I was the one that got him to produce the birth certificate, and I think I did a good job.”

Mr. Trump did exactly what Mrs. Clinton wanted him to do. He acted like himself, including his standard, glowing appraisal of his own business successes. There are a lot of differences between running a business, in which the goal is to make money and protect the bottom line, and running a country, a position in which you must worry about people.

I guess in Trump’s mind running a business and running the country are the same thing, but it simply isn’t analogous.

Throughout the debate, Mr. Trump interrupted both Mrs. Clinton and moderator Lester Holt, who attempted to keep the debate moving along smoothly. Mr. Trump’s ego and dominant personality would not allow him to be professional; instead he was the loud mouth, the same old ignorant Donald Trump we saw at the Republican primary debates.

Mrs. Clinton, on the other hand, was calm and professional. She was clear with her answers and they were fact checked. Whether you love or hate Mrs. Clinton, you cannot deny her readiness and preparation for Monday. She agitated Mr. Trump throughout with her greater command of the issues and her sly personal digs at Mr. Trump.

The latter was never more clear than when Mrs. Clinton aggressively bashed Mr. Trump on his views toward women,  saying that “this is a man who has called women pigs, slobs, and dogs.”

As the debate entered the final 30 minutes, Mrs. Clinton clearly had Mr. Trump rattled, not because she made cheap remarks about him but because she was so obviously more prepared, and actually deserved to be standing up there on the stage.

Mr. Trump appeals to the angry, disenfranchised, mostly white segment of America. Even though his unfiltered, oftentimes offensive remarks have worked in the past to get him to this point, I think things are going to start to crumble around Mr. Trump in the weeks ahead, as his antics further show the American people how unfit he is to be leader of the free world.