Waves of nostalgia can hit at any time. They tend to wash ashore more frequently in between graduations with their “look back, look forward” speeches and weddings. During these transition phases, we recall the days gone by, whether we’re suddenly comparing a memory from a few years to a decade or more earlier.

We watch our children stretch out surprisingly long arms to take a diploma and shake the hand of a school official, recalling how those hands used to reach up high to grab ours as we crossed the street.

We listen to their confident voices as they share detailed, measured and elaborate opinions about politics, sports, social issues or music. At the same time, we replay the high voices in our heads when they shared thoughts that weren’t so complex, as in “Jimmy Neutron is the best.”

When my wife and I walk around town, we frequently stop outside T-ball baseball games, where we soak in the figurative nostalgia bathtub. Johnny swings at seven pitches before he finally dribbles a ball foul. The exhausted coach encourages Johnny to “run, run, run!” Once the boy reaches first base, a small smile fills a round face that will get longer and leaner in the days ahead, until he reaches the stage where he rolls his eyes when people around him speak of sports because he and his razor stubble have tuned into the world of guitars and rock bands.

For some high school graduates, home has become a launchpad, where the NASA countdown to lift off for college will thrust them to a new location.

And then there are the brides and grooms, whose parents may recall their own weddings even as they smile at the way their children are planning to have people on stilts passing out hors d’oeuvres. The reason no one else thought of it, we think, is because it seems impractical, even though we don’t say that because we don’t want to rain on our children’s parade.

The parents of the bride and groom may remember the people who surrounded them at their wedding, from family members to important friends. Parents may have spent extra time searching through alumni directories or online listings to find the addresses of some of those important friends they haven’t seen in decades to invite them to another can’t-miss wedding.

Parents may stare at their children and recall the long journey from the cooties and a fear fascination with love and romance, to this moment when their child plans to travel the rest of his or her life with this marital partner.

What good does nostalgia do? It offers an opportunity to reflect on the past, while overlaying memories with current experiences. While we’re dancing to music we heard years ago, maybe at our own weddings or on an early date with a future spouse, we may close our eyes and reconnect with the younger version of ourselves. We remember who we were and who we wanted to be. We may laugh, realizing how far we have to go, or boost our resolve as we observe the changes in ourselves and others around us that encourage us to believe that anything, improbable or difficult though it may seem, is still possible.