In January 2011, I wrote my first entry in a five-year diary.

Designed by the graphic artist Tamara Shopsin, it’s set up so that entries on the same date line up one beneath the other. For every entry you write, you can scan up to see what you did on that date one, two, three, and four years ago. Shopsin, I’ve since learned, was inspired by a New York Times article about Florence Wolfson Howitt, who kept such a diary from 1929 through 1934, when she was a privileged Jewish teenager growing up on the Upper West Side. In 2003, a Times reporter, Lily Koppel, discovered the diary among the trash at a building on Riverside Drive. Koppel found Howitt still living in Florida; her story about a slice of recovered personal history and the passage of time became a book, The Red Leather Diary, published in 2008. (Howitt died, at 96, in 2012.)

“You’ve brought back my life,” Howitt told Koppel at one point, as she thumbed through the crumbling diary.

I started keeping my version on a whim. It was a milestone birthday year when I started, and I suppose my thoughts had begun to turn to the parts of my life I’d already lost, either through the death of loved ones or as a result of my own crumbling or highly selective memory. Like most parents (especially in the pre-Facebook era), I wished I had kept a better record of my kids when they were young. Yes, we took photographs and shot videos (now trapped on 8-millimeter cassettes), but gone are the conversations, the routines, the little things that made us laugh.

There’s not much room for reflection in the tiny spaces allotted in my five-year diary, but even in telegraphic form the diary helps me preserve big moments and the mundane things that I might otherwise forget. In that first year there was a Very Big Moment — a health crisis that kept me away from the diary for a week. The handwriting changes abruptly as my wife takes over, chronicling my hospital stay and my recovery. My chicken-scratching returns in early May of that year. I have almost no memory of the time I was “away”; in more ways than one, my wife “brought back my life.”

There were other Big Moments, but in some ways what I like most about the diary is the way it captures the boring, everyday stuff. What we ate for dinner. What we watched on television. Who we chatted with at kiddush. By my desk, I keep a framed quote from Irving Howe’s World of Our Fathers, in which he describes how the old Forward newspaper took an interest in the ordinary goings-on among its immigrant readers. “Nothing seemed too mundane for the Forward staff,” he writes, and as a result the paper remains a record of how people actually lived their workaday lives.

If you’re typically lucky, a five-year diary can remind you how little has changed over the years. My Shabbats, for example, are almost eerily identical. A typical Tuesday in 2012 is not that much different than a typical Tuesday in 2014. Considering the alternative, there is comfort in this sort of recurrence. (What’s the supposed Chinese curse: “May you live in interesting times”?)

But monotony can also seem like a judgment and a goad to shake things up a little. Psalm 90:12 says, “Teach us to number our days, that we may get a heart of wisdom.” There are various interpretations of the verse, but the one I like most suggests that we’re being told to make each day count — or, as it says in the old Silverman prayer book, “May no day pass without bringing us closer to some worthy achievement.”

On New Year’s Eve, I wrote my last entry of 2015, closing out the diary and the first half of the ’teens. I’ve already started on a new diary. (I encourage you to do the same; search 5 Year Diary at your favorite bookseller.) It’s daunting to hold a book of mostly blank pages without knowing how they’ll fill up, but that’s just the objective correlative for how humans experience the future. And it’s exciting, kein ayin hara, to imagine what these next 1,827 days will bring.

Our metaphors about time are mostly about what’s lost. Time slips away. We lose time, or we waste it. The diary is a small hedge against this kind of loss. Each entry is like a receipt for a day that’s been stored away — I may never get the day back, but at least I can remember what it looked and felt like, and how I used it when I had it.

In Saul Bellow’s Mr. Sammler’s Planet, a character says, “Everybody needs his memories. They keep the wolf of insignificance from the door.” I read the book in my 20s, and didn’t know what that possibly meant. I do now.