A smell can drag you back into a memory faster than any photo can

Marcel Proust described it first: a single bite of a tea-soaked madeleine flooded him with a childhood memory he hadn't consciously thought of in years. Psychologists now call this involuntary memory — recollection triggered without deliberate effort, most powerfully by smell and taste. Brain imaging suggests the olfactory system connects unusually directly to the amygdala, which may be why a scent can feel more like time travel than any other sense.

— Marcel Proust, In Search of Lost Time — Concept later studied as 'involuntary memory'
Go deeper: get the book →