I slept little that first night in Cuernavaca though we were exhausted, having flown twelve hours through the Christmas midnight from Wyoming, via Dallas, and then driven sixty miles south over the mountains that ring Mexico City to reach the home of the Sanchez family at two in the morning. But even in those very early hours, someone across the gulley from our house was repeatedly and mournfully singing “(I Did It) My Way” on a karaoke machine. Then intermittent volleys of firecrackers and the deeper gut-sound of celebratory gunshot ricocheted through an increasingly restless dawn until dogs and roosters were also in full voice and any hope of sleep had to be abandoned.

I hadn’t come to Mexico to write about the place or the people. My youngest daughter, Cecily, and I had come south from the depth of a Rocky Mountain winter because sometime the previous summer—in the process of writing about my mother’s life in southern and central Africa—I realized I had lost the second language of my youth. I knew, for example, that there are at least three Shona words for dusk—marirangwe, “when the leopard calls”; rufuramhembwe, “when the duiker grazes”; and rubvunzavaeni, “when visitors ask for lodging”—but I had had to look for them in my spine-snapped copy of Shona Companion: A Practical Guide to Zimbabwe’s Most Widely Spoken Language.

The knowledge of that loss of language troubled me, not because I expected to use the language much again (although my parents now live on Zambia’s border with Zimbabwe where a dialect close to Shona is spoken) but because I sensed that without access to that old tongue I had lost a hardwon part of myself. Until I was thirteen, I lived with my parents on a drought-prone farm pressed up against the minefield that separated Rhodesia from Mozambique. The Rhodesian government—engaged by then in an entangling civil war against insurgents who wanted to liberate the country from white-minority rule c...