My two-year-old daughter has been in a button phase. She sorts and describes sparkling buttons, heart-shaped buttons, thick and thin buttons, knobby and smooth buttons, and a couple we found that look like daisies. She is learning to separate and group unlike and like things. This new interest was inspired by the joy she’s found in a story we’ve been reading: one of Arnold Lobel’s Frog and Toad stories, “The Lost Button.”

In the story, after a long walk together, Toad realizes one of his buttons is missing. Far and wide, Frog helps him to search for it. They find many buttons, but none of them are Toad’s: one is square, not round; another has two holes, not four; and so on. Lobel depicts angry Toad jumping in the air with clenched fists. He screams, “The whole world is covered with buttons, and not one of them is mine!”

In frustration, Toad runs home and slams the door, only to find, there on his own floor, his lost button. Finger to his mouth, Toad turns penitent, reflecting, “What a lot of trouble I have made for Frog.” Pulling out his sewing box, he transforms the ordeal into a gift for his patient, steadfast friend. In a hopeful inversion of the angry Toad picture, the last image of the story shows Frog jumping up “for joy,” fingers spread open. He wears Toad’s coat, now ornamented with the buttons the two friends found together.

Among lists of great literary friendships, Arnold Lobel’s Frog and Toad ought to sit at the top. Classically odd-coupled, Frog is lean and bright green, and a good head taller than stockier, brown Toad. Frog is buoyant, optimistic, and creatively flexible when things go awry. Toad, on the other hand, is melancholic and often angry.

Their friendship plays out over twenty stories comprising four collections of five stories each. Their foil makes good comedy, but that’s not all. The pair present a question. Throughout their stories, I have to wonder what the fast, chipper amphibian sees in the slow, stubborn one. Like, why does he like him? Couldn’t he do better? In categorizing like and unlike things, I’m not sure I’d pair them.

But in spite of their humorously mismatched personalities and tendencies—and perhaps because of them—Frog and Toad’s friendship has a few valuable lessons to offer readers of every age.

01. Friendship is possible even in the most implausible circumstances.

Over and over again, Toad says, “Blah,” and stays in bed. In “Sledding,” he storms home after mismanaging a sled. In “The Story,” he is unable to think of a story with which to comfort Frog and makes himself sick trying to do so. And in “Cookies,” after a gluttonous sweets fest, Toad rejects Frog’s efforts to temper themselves. Having enjoyed one after another “last” cookie, Frog declares they need willpower to stop. After a series of locks and keys, they finally give the treats to birds, who fly away with them—a nice symbol of freedom from vice! Frog rejoices, “We have lots and lots of will power.” Yet Toad declares, “You may keep it all, Frog. I am going home now to bake a cake.”

This is supposed to be funny, and it is. But the humor doesn’t stop it from being a bit troubling. Frog offers to improve his own character along with Toad’s, and Toad is almost blind to it.

Aristotle says that equality is necessary for true friendship. Like goes with like. While Frog and Toad are perhaps equal in taste and age, Frog seems to possess more virtues and to a greater degree than Toad. How can friendship between the two be possible?

Here, Lobel weaves something beautiful, and though subtle and humorous, it’s clear enough for a two-year-old to absorb: Toad seems aware of Frog’s superiority in virtue. He clings to their friendship almost as a child clings to his parent.

Frog never lords his goodness over Toad as a weapon (which would make him less good, anyway); he genuinely enjoys him, and must forgive all of Toad’s “Blahs” and going back to bed. In return, Toad never swallows up Frog in his pessimism. He returns gratitude and loyalty when Frog meets him.

02. Friendship cannot exist where one person is more important than the other.

In the last stories of every collection, Toad worries or wallows in loneliness. Specifically, he becomes anxious that he has lost Frog—either completely from this good earth, or as his best friend.

Most poignantly, in “The Dream,” Toad sees himself performing on a stage as the greatest Toad in the world, each act grandly announced by a loud voice, while Frog cheers in the audience. It’s wish fulfillment. As someone who is easily frustrated by simple tasks, what joy for Toad to find himself playing the piano with dexterity, while his friend admires him.

Mysteriously, Toad’s grandeur has a deleterious flipside. With each incredible act of Toad’s, Frog shrinks, applauding all the while, until he disappears entirely. When Toad realizes Frog is gone, the voice is announcing his next act. But Toad screams, “Shut up! Frog, Frog, where have you gone?” He prefers Frog’s company to his own grandeur. The presence of the latter without the former makes him panic.

Lobel reminds us that whenever a friendship centers on one person over the other, the other is lost. There is no friendship of one.

03. Patience is tantamount.

Equality may play into true friendship, but it’s nearly impossible to achieve, faulty as we are. And seeking measure for measure absolutely destroys friendship. Frog and Toad are excellent friends because they seek the other’s good more than their own, imperfectly, with renewed attempts in each tale. And although each accepts the other as he is, there is no license to be complacent in their faults. Each lovingly encourages the other to be better.

But I like best the lesson on forgiving moods of melancholy and bursts of temper. The lesson is simply that love is patient. Frog is patient with Toad. More and more, I see an idealized mother-daughter or father-son dynamic in the pair, thinking of my children as little friends.

So I’m reminded to be patient with my sometimes Toad-like toddler, while she laughs at the amphibians’ misadventures and seeps in their friendship, and we look for missing buttons. One day, she’ll look with friends instead of me. We practice now becoming friends like Frog and Toad.