My mom described this phenomenon to me when she returned from a trip to India a few years ago, but I didn't really understand what she was talking about. She said that when she unpacked, she smelled India.
But now I understand, because the things in my suitcase smell like India, and part of me wants to put at least one thing in a plastic bag to save that smell. The sense of smell is so powerful, so able to transport you back to a particular time, experience, right into the memory. But scents are so fleeting, really.
India smells like spices, sweat, exhaust, dust, slightly sweet smoke of cow-patty fires, chai, intoxicatingly sweet flowers. I have one shawl, a peasant style that the shopkeeper was sure I didn't want, purchased for 30 rupees (about 75 cents) from the Haridwar street market that is completely infused with the smell of India. I don't want to unfold it, so that that smell stays trapped in the darkness of the fabric. It smells so good.