Toward the end of the debate, Trump questioned Clinton’s stamina. “I don’t believe she does have the stamina,” he said. “To be president of this country, you need tremendous stamina.”

But the irony was it was Clinton’s stamina that won this debate, and behind that stamina was her preparation. Trump grew less and less coherent as the night wore on, and his early spree of interruptions flagged as he was quickly forced onto topics where he hadn’t done the work to feel comfortable. Clinton, by contrast, grew stronger as the debate wore on, because she had prepared for everything the moderators threw at her.

There were many differences between the candidates on display in this contest, but the most consequential one was that Clinton displayed the basic personal qualities necessary to be president. Trump didn’t. She had done the work to know what she was talking about and to survive a high-stakes encounter with an unpredictable opponent. He hadn’t done the work, and it showed.

: The first debate featured an unprepared man repeatedly shouting over a highly prepared woman – Vox

Yup.