WASHINGTON -- "I think the retweet speaks for itself," said Donald Trump's senior policy adviser, Stephen Miller, about the candidate's posting of an unflattering photo of Heidi Cruz, juxtaposed against his own supermodel spouse.

"No need to 'spill the beans,'" the caption read. "The images are worth a thousand words."

Speaks for itself? What does it say? My wife's hotter than yours? This, folks, is where campaign 2016 has descended. As Fox News' increasingly invaluable Megyn Kelly tersely tweeted: "Seriously?"

It's going to take me a little longer than that to unpack the latest in Trump's menacing brand of misogyny.

Two points to begin. First, the flat assertion that candidates' spouses are off-limits goes too far. If they say or do things that are questionable, those activities are reasonable for an opponent to raise.

A historical example: former California Gov. Jerry Brown, running against Bill Clinton in 1992, raising questions about Arkansas state business flowing to the Rose law firm, where Hillary Clinton was a partner. "Let me tell you something, Jerry," Bill Clinton exploded. "I don't care what you say about me, but you ought to be ashamed of yourself for jumping on my wife."

And a more recent, roles-flipped matter: Trump raising Bill Clinton's conduct toward women after Hillary Clinton accused Trump of a "penchant for sexism." Bill Clinton is his wife's surrogate in chief. When she simultaneously deploys him and calls out Trump for sexism, the topic of Bill Clinton's behavior is fair game.

Second -- brace yourself for another point in Trump's favor here -- he had grounds for being angry about the way his own wife was used against him. The Facebook ad produced by an anti-Trump super PAC, "Make America Awesome," was outrageous and, though it seems like an odd word to use in this context, fundamentally sexist.

"Meet Melania Trump. Your next first lady," the ad said, above a revealing photo of her. "Or, you could support Ted Cruz on Tuesday." Easy to see how this might resonate with Utah Mormons at whom it was targeted, but it crossed the line.

At the time the photo was taken, Melania Trump was merely dating the candidate; she was a supermodel whose commodity was her looks, and whose job was selling them, which is what she was doing in the pages of GQ. There is no reason to think that Melania Trump would be anything other than a proper, and properly dressed, first lady. There are ample other reasons to vote against her husband.

But if that ad went too far, so then, characteristically, did Trump. The ad wasn't Cruz's doing, but Trump lashed out at him anyway. "Lyin' Ted Cruz just used a picture of Melania from a G.Q. shoot in his ad," Trump tweeted on Tuesday night. "Be careful, Lyin' Ted, or I will spill the beans on your wife!"

Must it really be said that threatening your opponent's spouse is out of bounds? Yes, apparently it must. That the alleged beans may have involved Heidi Cruz's struggle with depression made Trump's move all the more despicable.

And, in the "but wait, there's more" infomercial that is the 2016 campaign, it didn't stop there. When Cruz called Trump a "coward," Trump, naturally, counterpunched, retweeting the unflattering spousal photo spread.

And revealing, once again, his fundamental sexism. In Trump world, women are valued, or not, primarily for their attractiveness. "You know, it doesn't really matter what they write as long as you've got a young and beautiful piece of ass," Trump told Esquire in 1991. Women's looks are the focus of his interests, personal and professional (see Trump's investment in beauty pageants), and tend to be the focus of his female put-downs.

If anything, Trump has been -- by Trump standards -- restrained on this front during the 2016 campaign. He may not know better than to remark favorably on a professional woman's appearance -- hello, it's 2016! -- but he has managed, mostly, to refrain from looks-based bashing. Less "face of a dog," more "total fool."

Still, there are moments, when challenged, that he can no longer contain his instinct to demean based on attractiveness. Thus, Trump's reference to Carly Fiorina and "that face. Would anyone vote for that?" And thus, I think, Trump's outsized fury at Kelly: The very fact of her attractiveness heightens Trump's anger at her impudence.

And so it should surprise no one that we have descended to the Melania-Heidi faceoff, courtesy of Trump's retweet. Which does, indeed, speak for itself.

(c) 2016, Washington Post Writers Group