“Ponder for a long time whether you shall admit a given person to your friendship,” Seneca counseled two millennia ago in his timeless meditation on true and false friendship, “but when you have decided to admit him, welcome him with all your heart and soul.”

I often ponder friendship — that crowning glory of life — and the strain of protecting its sanctity from the commodification of the word “friend” in this age of social media. Adrienne Rich exposed the naked heart of it in her bittersweet assertion that “we can count on so few people to go that hard way with us.” I side with astronomer Maria Mitchell in that the few who do accompany us intimately along the walk of life shape who we become, and with poet and philosopher David Whyte in that “all friendships of any length are based on a continued, mutual forgiveness.”

But what, really, is the meaning and measure of friendship? Like most things of beauty, it is slippery to define yet deeply felt. Paradoxically, devastatingly, it is often recognized most acutely through its sudden loss. It lives most intimately not in the grand gestures but in the littlest things that add up, in the final calculus of life, to the bigness of any true bond.

That is what children’s book author Sandol Stoddard and illustrator Jacqueline Chwast explore with immense sweetness and sensitivity in the 1965 gem I Like You (public library) — one of the tenderest and most touching presents I’ve ever gotten, from one of my dearest friends, and the platonic-love counterpart to Elizabeth Barrett Browning’s classic romantic-love sonnet “How Do I Love Thee?”

Stoddard — who wrote more than twenty children’s books and the first major book advocating for human-centric end-of-life care, lived to be 90, and died the mother of five children, ten grandchildren, and ten great-grandchildren — was once asked to identify the underlying theme across all of her books.

She answered simply, “Love.”

And love — that sweetest, most knotless and untroubled kind — is what radiates from these simple, surprisingly profound verse-like meditations on friendship, illustrated with the kindred sensibility of Chwast’s simple yet richly expressive black-and-white line drawings.

Published the same year as Love Is Walking Hand in Hand — that charming catalogue of little moments that define love, channeled by the Charlie Brown, Lucy, and the rest of the Peanuts — the book confers upon friendship the delight and dignity we tend to reserve, foolishly so, for romantic love only.

More than half a century later, I Like You remains a timeless treasure, as delicious to give and as it is to receive. Complement it with Little Prince author Antoine de Saint-Exupéry on losing a friend and Kahlil Gibran on the building blocks of meaningful connection, then revisit two other charming picture-books about friendship from the same era: Ruth Krauss’s infinitely delightful I’ll Be You and You Be Me, illustrated by the young Maurice Sendak, and Janice May Urdy’s clever reverse-psychology gem Let’s Be Enemies, also illustrated by Sendak, just as he was beginning to dream up Where the Wild Things Are.