Some scents are unforgettable. Recently, my husband mentioned he was running low on shaving cream. “I’ll pick some up,” I offered. “Can you get this kind?” he asked, showing me the can. “I love the smell—it’s the kind my dad always used.” I smiled, recalling the time I had been momentarily taken back to my childhood when I got a whiff of the same shampoo my mom used to wash my hair. For both Tom and me, the fragrances had brought an emotional response and pleasant memory of people we loved who were no longer around.