I once interviewed Donald Trump for a magazine story. The topic was rivalries, which seemed like a natural for him. But he was so bombastically short on specifics, so braggadociously vague, that in the end there was nothing to quote. I left him out of the story.

So I was surprised recently to learn, by way of an article in The New Yorker, that Mr. Trump had, in fact, quoted me in a passage from his 2004 book “Trump: Think Like a Billionaire.” I would not have imagined that I had ever written anything he would want to quote.

It’s true that I had written about him in my book, “The Natural History of the Rich: A Field Guide,” published in 2002, but there was nothing remotely flattering there, as a glance at the index seemed to confirm:

Trump, Donald

hangingflies, compared to, 16

inherited wealth and, 266

intimidating eyebrows of, 87

Maples’s rating of, 248

multistory erections of, 94

reproductive asset management of, 225

The book was a work of tongue-in-cheek sociology, based partly on the premise that rich people often act like animals in the wild. But as I flipped through the references to Mr. Trump, it dawned on me that my animal analogies had been far too modest.