It’s been six years since our oldest child graduated from high school. Hence, his was the first senior portrait to claim a spot on the wall in our front hall.

Three years later, a smiling depiction of our darling daughter was added, strategically hung to allow room for one more. For three more years, that spot stood empty as our youngest son trailed along, making his lone way through high school and preventing his parents from seeming too “old.”

He gradually chalked up the days, weeks and finally years of algebra, Spanish, “The Scarlet Letter” essays, concerts, track meets, chemistry and pre-calculus until, one mid-winter’s day, the photography studio receptionist called.

“Your order is ready for pickup,” she chirped.

And there it was: A 10- by -13 picture of our “baby,” looking far more mature than the carefree sixth-grader he was when his older brother kicked off the trio of sibling commencements.

At last our collection was complete, and while there was satisfaction in seeing all of our children represented in that singular place of honor, a creeping aura of finality also infiltrated our senses.

How had it escaped us that each time we added a frame, we were one step closer to emptying our nest?

Now our wall is filled with glowing shots of three fresh young faces, but our house is that much nearer to being a dwelling occupied primarily by an AARP-aged couple. It’s easier to pretend you’re still “young” when you’re darting about from sporting event to concert to parent-teacher conference at the speed of light, but it’s a certainty that next September will introduce a new pace of life for us.

As the calendar pages yielded themselves one by one through this hectic senior year, the demand for photos increased.

“Senior pictures needed for yearbook placement by April 6,” read a message from the high school. “Send eight pictures from babyhood through high school,” urged the church office assistant as a senior tribute was being organized. Choir and band directors sought snapshots for end-of-year slideshows, too.

All the while, we had the benefit of not only the smiling, still-life senior on our wall but also the flesh-and-blood kid whose perpetual trail of scattered books and papers, guitars, shoes and snacks left no doubt that we weren’t the only ones at home.

On Friday evening, still more photos will be snapped as our son and his nearly 200 classmates don their caps and gowns, collect their diplomas and proceed through the local grad party circuit, ready to down countless red and black M & Ms and more frosting-laden cake than any healthy human should consume in eight months.

Come September, as this unique 18-year-old heads off to college - likely leaving behind his pet bearded dragon for our care and feeding - the stacks of pictures remaining in his wake may seem more precious.

Occasionally, we might find ourselves pausing at the foot of our stairs to observe three special portraits, praying that the young adults represented in them will have grace-filled days in which they exercise wisdom, courage and kindness. Our triptych is complete, but their journeys through life are only beginning.

Class of 2019, congratulations on your graduation! And please, smile for the camera; your mom will thank you for it.