Do we ever really know another person? How long might that take? Twenty years can’t possibly be enough if my example is any indication of the scope of the discovery.

My husband took note recently of the fact that I opt to have the time displayed in 24 hour format when possible. He noticed this as the evening grew dark and visiting friends wondered about the prudence of getting their kids home to bed. I woke up my phone first as it was sitting rather rudely before me on the dining room table.

“20:12?” DH asked. “Your phone is set to military time?“

Keep in mind that we’ve known each other for almost 20 years, and been married for most of those.

This becomes rather more amusing if you’ve ever visited my home, ridden in my car, or viewed any of my electronics. All of these conditions have been met by my husband, with most of them occurring on a daily basis.

Both of my children have had noisy arguments with me within DH’s earshot about my insistence that they learn to read a 24-hour clock and an analog one before I will buy them the digital watches they oddly covet.

In our kitchen, the microwave oven and a digital clock give the time in 24 hour format. Come to think of it, DH has always complained about being unable to find the time in our new house. Perhaps he thought those were kitchen timers in constant use?

In the communal study the kids and I call the “workroom,” there is a digital clock set to 24 hour time displayed prominently on DS’s desk. You can’t walk through the room—which DH must do to reach his own office—without seeing its face.

The clock in my minivan displays 24 hour time and it has since I set it on the day I drove it home.

The sunrise clock on my side of our shared marital bed shows military time, too. To be fair, though, DH has his own clock on his side so he needn’t read mine with any regularity.

Are you sensing the pattern? I don’t think this is a subtle one.

I prefer the efficient notation of written time in fewer characters. I like the frequent tiny mental math problem of subtracting twelve. I don’t like the look of the abbreviations for ante- and post meridiem unless they are in small caps, and those can be annoying to implement (in WordPress, for example.)

None of these reasons matter in the least, of course, though it’s amusing that the same husband who teases me for clinging to the archaic Imperial system of measurement seems to have a similarly irrational preference for a less concise system for measuring time.

I pronounce the time in the standard twelve hour format, so, without his ears to help with the heavy lifting of comprehension, DH can be excused for never noticing what was right before his eyes.

It’s easy, after a decade and a half, to assume we know it all about a partner and a constant presence. It is very often true that I can predict exactly what DH will say, or choose, or prefer.

But, then again, human beings are awesome in their complexity, and my mate is no exception. Every day, each of us goes out into the world, changes it, and is changed by it. We grow. We evolve. Hopefully, we learn a little, too.

We aren’t the same young people who met online, like proper nerds, dated, and fell in love. We’re older, saggier, and otherwise more time-worn.

One of us prefers miles and military time; one of us is all metric, but goes to bed at 8 o’clock instead of 20:00.

The joy of it is being tickled by discovery this far in. The wonder is that we still have so much to discover, and so much desire to do so.