THE WAIT was worth it.

Bill Watterson, that master of timing, waited decades to give a truly in-depth interview. As he did with his beloved strip, the “Calvin and Hobbes” creator knows when and how to aim for, and deliver, the exceptional. He was in the interviewer’s chair for one of the best cartoonist Q&A’s published last year (his sit-down with the “Cul de Sac” creator for “The Art of Richard Thompson” retrospective book).

Now, as the subject himself, Watterson has provided one of the best bound cartoonist Q&A’s in recent memory. For any true fan of cartooning, it is a must-read, a must-buy, a must-pick-up.

This rare sitdown, with Jenny Robb of the Billy Ireland Cartoon Library & Museum, at the Ohio State University, will likely long stand as the definitive Bill Watterson interview.

For years, the cartoonist didn’t make public comments. Now, in a single wide-ranging and revealing and illuminating and engrossing and self-deprecating and poignant and, of course, deeply funny interview, Watterson has proved more generous than we perhaps could have ever hoped for.

Bill Watterson has delivered a gift, a trip down memory lane that is populated densely on each side with personal and professional insights — some grippingly specific, some that ring universal, many that resonate as both.

The occasion for this interview is linked to the Bill Watterson retrospective curated by Robb and exhibited last year at the Billy Ireland galleries (in a dual show with a Richard Thompson retrospective) and this year at Angouleme. Tomorrow, Andrews McMeel, the parent company of Watterson’s syndicate, is publishing “Exploring Calvin and Hobbes,” the ravishing exhibition catalogue from that retrospective — a 152-page beauty that, like the show itself, is organized around such themes as the seasons that rippled through “Calvin and Hobbes” like supporting characters.

And “Exploring Calvin and Hobbes” the Book, arriving 20 years after the adored strip sledded away for the final time, finds Watterson in the late-summer of his content.

Of his dual show with Thompson, Watterson said to me last year: “All this inspiring work in a big, new museum — it should be a lot of fun to see, and I’m very happy to be a part of it.” And as of late, Watterson has seemed to enjoy being a part of the larger comics world, too, providing poster art for Angouleme (as the festival’s 2015 president) and the recent documentary “Stripped”; creating new public art to benefit a Parkinson’s charity; and coming out of comics-page retirement last year to draw several days’ worth of Stephan Pastis’s “Pearls Before Swine.” Now, “Exploring Calvin and Hobbes” marks the second book Watterson has authored or co-authored in just four months.

It’s so great to have Watterson’s voice, both on the page and off, re-engaged in the comics conversation. Which brings us to The Interview, which, at a roomy 35 pages (including inviting spot art), is joyously more than one-fifth of this book. So just what does Watterson touch on in this Q&A?

The better question: What doesn’t he touch on?

Posing the questions is Robb, curator at the Billy Ireland library and museum, which holds Watterson’s collected works. She provides the cartoonist plenty of room to take his answers, like a deftly steered sled ride, to some pretty exhilarating places — launching early on into some “Rosebud” moments from Watterson’s happy and mostly sheltered midcentury Ohio childhood, save for a couple of more harrowing camping trips with ever-daring Dad.

The true worth of this interview is that it’s as multifaceted as a jewel. Watterson offers enough about his upbringing that each fan can learn and infer (and guess) connections to the comic strip, and what traits and touches of the feature might have been directly inspired by his childhood. Following the trail of such small discoveries is like hunting for Easter eggs.

Perhaps most revealing, though, is the portrait of a young man as a comic artist. Watterson is not big on the “quest” narrative (particularly when watching animated films), but from his experience, he does map out a humble, oft-self-deprecating journey. Here and elsewhere in the book, we can appreciate what artists most influenced Watterson — from the fluid precision of his fellow Kenyon College alum Jim Borgman (the longtime Pulitzer-winning Cincinnati Enquirer cartoonist, and the co-creator of “Zits”), to the radically disruptive lines and ink-splats of Ralph Steadman. (As well as, naturally, Charles Schulz and Walt Kelly, among others.)

Watterson’s path to syndication, littered with rejection notes, is still a great object lesson in persistence and self-conviction (no selling-out of his vision in order to draw suggested robot characters), and in wise recognition of smart syndicate advice (the bangs over Calvin’s eyes were removed at the last minute before launch) and the ability to capitalize creatively when, lo and behold, you suddenly discover your character has his own “voice.”

Watterson is also honest about the true challenges of a syndicated life, especially when you set such an exceedingly high bar for yourself:

* Providing a peek inside the driven mind, Watterson says: “The intensity of pushing the writing and drawing as far as my skills allowed was the whole point of doing it.”

* Of coping with the realities of syndication: “The strip deadlines are so relentless that simplicity and speed become great virtues.”

* And of being ascribed great philosophic depth within his inky panels: “If you draw anything more subtle than a pie in the face [in comics], you’re considered a philosopher.”

Watterson admits to panic and “meltdowns” when licensing squabbles put him behind the 8-ball of extreme (and expensive) deadlines for a half-year, and acknowledges his wife Melissa’s crucial role in managing schedules and a household, as he walled himself off from much of the daily world in his passionate maximization of his abilities, like an Olympian athlete on a decade-long regimen. In this way, we also glimpse some of the truths that often come with being the partner of an artist.

Similarly, Watterson paints the physical truths of such near-monastic commitment: He was in his mid-20s when the strip began, and in his mid-30s when he walked away. Were he to regularly return to the art board now in his 50s, he admits, he would be battling arthritis and back pain.

And speaking of that walking-away: Watterson dispels and clears up rumors that arose around his departure. Some have speculated that fights over licensing, or page space, or shifting newspaper realities, led to his retirement from the page in December of 1995. The cartoonist’s thoughts on leaving, and licensing, are more nuanced and less drama-driven than that.

“A comic strip, like anything else, has a natural life span,” says Watterson, like a man ever-cognizant of at what stage and state his strip was at.

“Art has to keep moving and discovering to stay alive,” adds the cartoonist, emphasizing that “the last few years of the strip, and especially the Sundays, are the work I am the most proud of. This was as close as I could get to my vision of what a comic strip should be.”

Watterson also weighs in on the crumbling of newspaper syndication as both business model and assurance of huge audience share. He offers thoughts on webcomics as both more democratic and less lucrative:

* On reading online comics vs. pre-curated newspaper comics: “I like comics more than most people, but I don’t want to personally scavenge for them.”

* On the expectation that online comics be free: “When we don’t pay for what we consume, we’re exploiting people’s talent and hard work.” (And related to that, let’s hope people and outlets don’t “pirate” this interview without paying; at least until the museum offers it someday for free. As Calvin himself might bellow: “Avast, you online pirates!”)

* On the too-quick clickability of the webcomics experience, vs. the daily dose on a newspaper page: “Our connection to comics is getting more fleeting and superficial.”

Mostly, though, Watterson sounds eminently grateful for the audiences he got, in the era he first got them, in a format and model that played to so many of his strengths. “I just knew it was time to go,” says Watterson, now a family man in his native Ohio, seemingly at peace with his place and achievement.

Yet “Calvin and Hobbes,” so beloved as a strip ultimately about friendship, continues to find new young readers. And so this new book is not only a treasure-trove for longtime fans; its once-in-a-lifetime interview is also a road map of invaluable, transferable realities for the next generation of creators.

Tomorrow, Bill Watterson gives you a humble gift. Take it. For at last, your wait is rewarded and then some.

Time to go exploring.