When did I look away

Walking down the street I could always smell when someone had been smoking pot. It's something you don't really forget, the sweet smell, kind of nauseating. And it's something you can't be wrong about, it's not like incence, not like herbs, not like scented candles...

Sunday I was in a museum and there were lots of children around, it was a Pixar exhibition. I walked past a group of kids and instantly smelled the sweet, kind of sour smell of infant formula. That's something else you can't be wrong about. Once you've smelled it once, and had it spat back all over you, the smell is forever stuck on your memory.

When did I look away and this happened?