Show me a person who has no true friendships and I’ll show you someone with little if any talent for generosity, which is a muscle built through interactions with those who have no biological or legal claim to you but lean on you nonetheless.

Show me a person who has no true friendships and I’ll show you someone who can’t see the world through another’s eyes. A novel or movie gets you only so far down the road to empathy; to go the distance, you need more intimate, immediate experience of hurts and aspirations not your own. You need friends.

Show me a person who has no true friendships and I’ll show you someone with no adequately moderating influences on his whims, no sufficient cushion for his moods. I’ll show you a full-blown narcissist or full-throttle paranoiac or some combination of both.

I’ll show you the president of the United States.

On Tuesday, two of his campaign aides, Corey Lewandowski and David Bossie, published a book about their time with him, “Let Trump Be Trump.” It’s a cunning volume, adulatory on the surface but with just enough grime underneath to promote sales.