PHILADELPHIA — Having served as Australia’s first female prime minister, I often get asked for advice by bright young women interested in politics.

What sustains someone through the rigors of modern politics, I tell them, are passion and purpose: knowing what you want to achieve for your nation and the world. Then I tell them to build a sense of self that can survive all the ugly sniping.

This week at the Democratic National Convention, where I participated in a forum on women and leadership, I’ve been asked what advice I’d have for Hillary Clinton as she seeks to become her nation’s first female leader. I’m not egotistical enough to think that the most qualified and prepared presidential candidate the United States has ever seen needs my advice on policy. And she needs no lectures on sustaining a sense of self when under news media scrutiny or attack by her rivals. Few politicians have shown more resilience than Mrs. Clinton.

But even someone of her vast experience has been buffeted by what I call the “curious question of gender.” She knows what it’s like to be the subject of the stereotype that a powerful woman cannot be likable, that if she is commanding then she must be incapable of empathy.

If a female candidate notes the sexism of all this, she is told — as Mrs. Clinton has — that she’s playing the “woman card,” or is fragile, or a whiner.

Mrs. Clinton should not have to deal with this alone. Every Democrat, every Republican, every person who believes that women and men are equal should call out any sexism.

When I was prime minister, I created a carbon-emissions trading program. The debate grew vicious, with the leader of the opposition attending a protest next to signs that described me as a witch and a bitch.

No one called for my execution by firing squad, as a supporter of Donald Trump did for Mrs. Clinton, but a radio talk-show host did say I should be put in a bag and dropped in the sea. Witches can’t be drowned, I cynically joked.

I have often reflected how powerful it would have been if, at that moment, a male business leader, especially one who opposed my policies, said, “I may not support the prime minister politically, but Australia must not conduct its democratic debates this way.”

Unfortunately, that never happened.

To my dismay, some of the young women who chat with me are not asking for political insights. Instead, they tell me that, having seen how I was treated, they have decided politics is too punishing for them. I always try to talk them out of this position. Sometimes I succeed.

In 2016, I hope there are many brave voices naming and shaming any sexism in the presidential contest. The next generation of potential female leaders is watching.

Julia Gillard was the prime minister of Australia from 2010 to 2013.