For the second and final time, I have put the SIM from the iPhone 6 I purchased last September back into a 2012-vintage iPhone 5. The first time happened after a shockingly revelatory lurch into anxiety I experienced shortly after buying the phone. I more recently decided I’d give it another chance for a couple of weeks, under more controlled circumstances, and I did, but it still didn’t work out.

The iPhone has been the greatest single discrete work of technology I have ever owned, and the 5, tall but tiny, feather-light and functional, and beautiful, epitomizes it for me. And yet I purchased the 6 to replace it sight-unseen, because I felt no regrets picking up that 5 to replace my screen-shattered 4, which had in turn retired my iPhone 3G years before. Everything about the phone objectively improved over both my previous two upgrades, making me feel safe with, even excited about, the third one.

That 3G, my first smartphone, transformed my life in ways I needn’t enumerate, because most any of my contemporaries will already know them (no matter the make and model of their own mobile device). I could nonetheless summarize the smartphone’s gifts to us as a permanent extension to the human nervous system that seems in some ways like the pinnacle of the climb started by ubiquitous home radio circa 1920. With my iPhone in my pocket, I felt for the first time always connected, always online. I know that this has improved my happiness, my relationships, my work, and my life in general immeasurably.

Like many others, and perhaps like you too, I found that I felt anxiety any time I accidentally left my phone behind, or its battery died, or I entered an area with no cell signal. Involuntarily dropping completely offline, losing that constant connectedness, felt like a kind of blindness. I began to adjust my personal habits to help make these unwanted events happen less often. And do you know what this was? This was self-care; this was hygiene, it was grooming.

My iPhone, the physical thing whose immediate position in space I always remain at least dimly aware of — another brush against my hip pocket, just to check — and which acts both as a way to sense and speak to the world I care about, this thing is part of my body. It is part of my body. I state this with less metaphor than a thoughtful Catholic discussing the Transubstantiation. I wasn’t born with it, and I won’t bleed if you rip it away from me. But it has become a part of my physical totality just the same, the package that gives my mind presence to the rest of the world, and enables it to know and change the state of things outside my skull, just as my skin and fingers and ears all do. If I somehow permanently lost my ability to use a smartphone the way I do today, I would feel diminished, as surely as I would if I suddenly lost an eye or a leg.

The morning after my 6 arrived, I reached as soon as I awoke to pick my iPhone up from my nightstand, just as I have every morning since the fall of 2008. Almost immediately I began to feel a creeping panic, though it took me a while to realize why. For the first time, and even though I’d changed it two times prior, this part of my body didn’t seem to fit the rest of me any more.

I mean, it worked the same; yes, another autumn had brought as always another revision of the phone’s operating system, but at core it didn’t work much differently than last year’s release. It was all its physical proportions that suddenly seemed wrong. So much larger than my phones of the last six years, in every direction, and significantly heavier too. I knew that going in, of course, but somehow I hadn’t expected that to mean that I could no longer effectively use it one-handed.

Try as I might, I found myself unable to find a comfortable, natural-feeling way to fit the thing in my hand. Its shape, curved along every edge like a worn-down sliver of soap, made this worse: it always seemed on the verge of popping right out of my hand, and more than a few times I did manage to fumble it so it fell flat on my chest. Worst of all, no way I held it allowed my thumb to reach every part of the screen. The ability to switch comfortably between one-handed, portrait-orientation use and two-handed landscape always felt like a defining feature of iPhone to me, and suddenly — literally overnight, from my perspective, there in bed — it had vanished, replaced with a quiet but clear insistence on exclusively two-handed use.

“I hate this phone,” I said to my partner, lying next to me. I felt horrified, and sick. I would have scarcely felt less troubled had I awoken to find my left hand replaced by a stranger’s.

That morning I called Apple in a panic. Doesn’t that sound so laughable? I can only laugh at it today, even though I can remember exactly how thoroughly confused and upset I felt. The lady who took my call treated me patiently and kindly, though, and knew just what to say to calm me down: I had two weeks to return the phone for any reason, and any Apple Store could easily downgrade me back to my old model if I still felt unhappy.

So, I gave it two weeks. It didn’t get better. I did come to like the thumbprint-recognizing “TouchID” feature, and I will miss the 64 GB of storage I chose to garnish the new phone with. (The old 5 I slink back to has a quarter as much.) But nothing I did made the phone ever feel at home in my hand, and after six years of conditioning, the rest of my body firmly wished to reject it as an alien intrusion. Perhaps most worryingly, I could feel my nascent RSI twinge when I stubbornly held it up one-handed for too long; I found myself taking wrist-exercise breaks when I wanted to read for more than a couple of minutes at a time.

I love, love the staff of the Providence Apple Store, which I would end up visiting for the first time (having moved from Boston to Newport, Rhode Island the month before). I have enjoyed plenty of excellent customer-service experiences at Apple Stores in the past (at least once I learned to always make a reservation before visiting with any need more complicated than grabbing a gadget off the shelf), but, perhaps energized by the novelty of my situation, the staff really bent over backwards to help me out this time in particular. They showed me how to swap the SIM between phones myself — don’t ask why that hadn’t occurred to me before — and sunk a whole hour or more bending AT&T’s ear to allow me to refund my phone.

When it became clear that, due to carrier rules separate from Apple’s — the refund window had closed a day earlier than I had thought — I didn’t feel so bad. That staffer gave me surprisingly straightforward advice about selling the 6 on Craigslist, while another worked on swapping out my old 5, whose broken lock button qualified it for an exchange under a recall. All this shuffling took around three hours, with a couple of staff hanging out well after closing to see all my issues tidied up, making small talk the whole time. While at no point did anyone try to talk me out of my decision, the two overtime staffers did express curiosity about it, and I told them some version of the same story you have just read.

I also expressed my sincere hope that Apple would continue to produce iPhones with 4-inch screens — no larger than the 5’s, but quite smaller than the newest models — in the future. The two staffers looked at one another. I know that they don’t know anything more about Apple’s longer-term plans than I do, but they have every right to feel secure in their best guesses.

“Well,” said one, doing his best to not disappoint me, “I think I’m looking forward to the watch.”