There are days I feel as though I’m 80. Other days, I’m 19 again. Most days I’m Martha, 64, married, poor eyesight, always struggling with my weight, trying to do better. Writing books, telling stories.

At this time of year, however, my mind is flooded with memories of sophomore year at Providence College. Of early snow and Christmas anticipation. And of a tragedy whose roots took hold 45 years ago. Yes, w...