Did she look presidential?

As silly as that sounds, that was part of Hillary Rodham Clinton’s job on Thursday in Philadelphia when she accepted the Democratic Party’s nomination as its presidential candidate. It was not just showing people who do not understand her and who do not trust her who she is as a person, or laying out her policy proposals, but also demonstrating that when she represents them on the world stage, she would do so with that hard-to-pin-down aura of leadership and power.

And she did. In her white suit, with her white crew neck underneath, Mrs. Clinton looked supremely unflappable: perfectly tailored and in control. Not a hair out of place (but some hair nicely waved). The kind of person who could carry the nuclear codes with aplomb.

But since she is someone who famously does her homework, she also used her clothes to do a little more.

That she chose to wear white at the convention did not at first seem particularly surprising. Mrs. Clinton has worn white jackets multiple times during the primaries, and when she joined Instagram she posted a shot of a clothing rack filled with red, white and blue jackets. On Thursday night, the pantsuit stood out against the blue background, and in the sea of people.