Lara Trump, Woman in Black at the Republican National Convention

It may have been conceived as a bit of a joke, a relatable snippet of fun for listeners. But it speaks to the fact that she was aware from the beginning that dressing was a part of her job. (And she noted on the podcast that her daughter had “a really cute Jackie O dress that I found her” and that her husband, Eric, had a new suit.)

The first day, when she sat in the stands with assorted family members (including, when he arrived for prime time, her father-in-law), she picked a bright blue sheath, blue and white being the other obvious shades for an American political convention. The second night, for her moment in the spotlight, she went in a different direction.

On her top she pinned not a bedazzled flag, which seems to be the R.N.C.’s female equivalent of the American flag lapel pin, but rather a ribbon brooch made from what looked like red, white and blue gems. It sparkled patriotically against the black as she recalled the events of last weekend and the moment that was, she said in her speech, “one of the most frightening moments of my father-in-law’s life.”

Yet it was a moment, Ms. Trump also said, that her father-in-law knew would be “defining” for the country, so “he hoisted his fist in the air.” In doing so, he created an image, she said, “not just for the people at the rally, not just for his supporters, but for all of America.”

Indeed, the photo of Mr. Trump with his fist in the air and blood smeared across his cheek has spread quickly in the days since (it is now on multiple T-shirts). Just as the words he cried as he raised that fist — “fight, fight, fight” — have become a chant of the convention, along with “Trump, Trump, Trump.”

As much as Ms. Trump’s speech acknowledged the power of the image, it also revealed a key truth about her father-in-law: In that instant of chaos and terror, Mr. Trump knew what he was doing. Creating a powerful visual has always been a key part of his communication. He understands how much pictures matter. And looking at her, listening to her, it was a family lesson she had clearly absorbed.