Some people make photo albums, collect antiques, or visit historic battlefields. Others keep diaries, plan annual family gatherings, or stitch together patchwork quilts in a tradition learned from grandparents. Each of us has ways of communing with the past, and our reasons for doing so are as varied as our memories. In a sweeping survey, Roy Rosenzweig and David Thelen asked 1,500 Americans about their connection to the past and how it influences...