I hate saying "it's a well-known fact" because I've learned that most "well-known facts" are usually wrong, but I guess it's a well-known fact that a scent can be the strongest memory trigger there is.
I opened up a box recently that I hadn't seen in a while, but I knew exactly what was in it. It was the box that the mouse came in for my very first computer: an 8 MHz laptop with dual double-density floppies, no HD, and a blue supertwist LCD monitor. Fortunately, it also had an output for a CGA monitor, which is how I usually used it. When I still lived at my dad's house, the old (then new) computer sat on a desk in a little nook in my room. Immediately to my left was a bookshelf where I kept all sorts of books that I might need while writing: dictionaries and thesauruses (thesauri?), my complete Lovecraft collection as well as other horror books, and various other reference books and my (cough) "black books."
On top of this shelf was the old mouse box, into which I had stowed my small collection of essential oils.
They were purchased by mail order from two or three different places. Various scents for various uses, some sandalwood, some cedar, and from Papa Jim's, one bottle of essential oil of myrrh.
I used to use a drop of myrrh the way most people use cologne, and by a drop I mean a drop. A very little goes a long, long way when it comes to essential oils. It was different, it has a kind of dark spiciness that I like in a scent, and there was at least one young lady in the years before I met my future wife who really dug it.
So I dug into the old mouse box today and extracted a still nearly full bottle of myrrh oil that is around 18 years old now. It still smells exactly the same. That's a nice thing about essential oils: if the container doesn't leak they'll last forever.
And what did the smell of myrrh immediately remind me of? Playing Ultima V on my first computer, nearly 20 years ago.
And then I thought of the girl. But I remembered the game first. I guess that says something, but I'm not sure what.