Here is part of a wonderful reflection on the sense of smell by Br. Paul Clarke, O.P.
I think that an area in which smell can still serve as a rich metaphor for the Christian life is in its relation to memory. It is a familiar experience to catch a sudden whiff of some familiar but nearly forgotten smell, then have a memory spontaneously spring to life. For me, the scent of fresh-cut grass calls up vivid, sun-drenched memories of baseball practice during hot Midwestern summers. The smell of an old glove, with its pungent bouquet of leather, linseed oil and sweat, has a similar effect.
Smells stimulate, conjure up memories, and also evoke a yearning, not mainly to relive the experience, to be “seventeen forever,” but to possess (return to?) the original wholeness of being, of which that experience was a glimpse, taste, and faint enticing scent. In this sort of nostalgia, there is an ache for the ultimate. There is, in the background of these memories, a single, towering memory, so grand that we hesitate to do more than hint at it. As Pope Francis puts it, “We possess within us a yearning for the infinite, an infinite sadness, a nostalgia—the nostos algos (homesickness) of Odysseus—which is satisfied only by an equally infinite response.”
Here is the whole thing