My 17-year-old daughter had a few friends over on Saturday night. They gathered in the back garden. It was low-key and last-minute - a goodbye to the summer holidays.
As night fell, the darkness twinkled with lots of tiny candles.
The next morning, we cleared up. My daughter was smiling in a sleepy kind of way. It had gone well. People had enjoyed themselves. As we picked up spent matches, empty cans and cracked plastic cups, my husband said, "Parties don't change, do they?"
And I thought, as I put out three bags of recycling, he's right. Everything else has changed. Facebook, texting, mobiles, internet.
But parties are amazingly similar to the way they were in the long-distant days of our youth. This is because:
1. Your very best friends arrive early. Everyone else comes an hour late.
2. The really cool people come three hours late.
3. The girls will find somewhere quiet to have meaningful conversations.
4. No one eats the French bread.
5. Teenagers smoke. Sad and weird - but they do.
6. Teenagers drink too much and get very loud.
7. Someone plays the Sex Pistols.
8. There are always a few gatecrashers.
9. There's always something - like the catflap - that people find hysterically funny towards midnight.
10. When it's time to turn the music down, someone keeps turning it up.
And finally, of course, there's that symbol of the morning after the night before - sitting there in splendid isolation among the squashed slugs and the crushed crisps and the fag ends on the flattened grass of our small London garden.
There it is: the big, battered, completely random traffic cone.