One minute you're escorting your five-year-old daughter to the school gate, the next you're popping a bottle of Veuve Cliquot and wondering where the hell the last 17 years went.
This is the problem with parenthood. As my grandmother told me when I was 20 — was it a warning, I've wondered in the years since? — children age you. I thought she meant they wore you down, put wrinkles on your face and grey hairs on your head.
But I understood much later, after I'd become a parent myself, the actual meaning of her statement: children are yardsticks for our own mortality. They are the mirror into which we peer for evidence of our senescence. They are hour glasses that cannot be laid on their sides, not even for a moment; instead, they must be turned over as soon as the last grain of sand has fallen through the flue.
They measure, in solid, physical terms, the swift passing of time. They morph from wrinkled newborns to plump toddlers to joyous tweens to surly teens to young adults to older adults — older than you were when you gave birth to them — so fast you are certain you've been cheated by a too-fast clock.
And so it was when, just last week, my youngest child wrote her final high school exam. Afterwards, she came home and threw out the school shirts too worn to salvage, the notebooks filled with information useless to a teenager, the schoolgirl persona she's hated since the day she was forced to adopt it.
And into the rubbish bin went a small part of myself, too, the part that has spent 17 years defined as the mother of my children, as the P&C member, the canteen helper, the cake baker, the lift giver, the sandwich maker. It had been quite some investment, too, for between them my three children had clocked up 39 years of schooling.
In my very first year as a school mother, I drove 120 km each day ferrying my older daughter to and from the farm we lived on to the rural school she attended. I was studying for a degree at the time and took in the car with me (along with my son and baby daughter) books to read while waiting for the school bell to ring.
In this, my final year as a school mother, I've merely waved my younger daughter goodbye at the front