When Quinn was three months old, my husband gripped my arm one day and told me solemnly “We are already 1/72 of the way through Quinn’s childhood living with us. Isn’t that so sad?”

At first I laughed a little, but then the significance hit me too. We couldn’t believe that any measurable chunk of time had already passed, that we would only have 71 of the same little chunks of time with her and then–bam– she would be off to climb Machu Picchu or serve as ensign on a starship, to join the Coast Guard, or maybe marry a drummer or hitchike her way through Mongolia.

I mean, caring for a child for 18 years sounds like FOREVER, until you start to carve into it. Tomorrow morning at 11:31 a.m. I will have a one-year-old daughter. No need for elaborate fractional representation, we are one year down and only 17 to go. And she’s not even walking yet! How on earth is she going to manage the SATs in only 16 years? How am I going to stomach passing over my car keys in only 15?

Time marches on, and kids are the coolest little time elapse models ever. I mean, with foals walking on their first day, how does a mare get any sense of the passage of time when she looks at her baby a year later?

I know it’s been a year because my little six-pounder is now close to 20 pounds. Her little bald head now has two and a half inches of blonde curls. She crawls, she stands, she waves, she jokes. She has eight teeth (though really I should say she has only 7.5). Her favorite book is “Where is Baby’s Belly Button?” and she likes to turn the pages all by herself. She wakes up only two or three times a night, compared to the six to eight times my little newborn did.

She points to let me know when a doggie is walking by, when a plane is flying overhead, and when daddy is walking up the stairs. She grabs my fork out of my hand and eats with it. She drinks her own water out of a glass and she likes spicy food. She pushes her arms through coats and shirts to help me get them on her.

I remember in the early weeks when she would stare at the blinds, taking in their contrast and unable to process much else. Now she crawls over and lunges at them, grabbing at the pulls and pushing her hand between slats to let the light in. She laughs hysterically at her good luck to be playing with them.

Tonight, after her bath, she parroted me happily, saying “Ah Dunn” over and over and over, as thrilled as I was to hear her sweet little voice forming (semi-recognizable) words in English. I can’t wait to hear more, even if it does mean the waning of her beautiful little babytalk.

Before Quinn, I was measuring time in my own years, and that was sure getting boring. A gray hair, a new job, a half dozen pounds lost or gained (or lost and gained), a new friend or two, a different internet provider. Once you’re done with your education and married, the milestones slow for a while. And then you have a kid, and that little one is hitting a milestone a minute, waking up different after every nap, synapses firing before your eyes.

I’m glad that we humans come out so tiny and helpless, that our brains double in volume over the first year and nearly again over the second. I’m glad babies have so much to learn, that they change so profoundly from week to week. As a parent, I am grateful I get to stare in wonder at this miraculous little measure of time, and give it raspberries on its sweet little belly any time I want.