My mother was expert at identifying illness through visual cues. A trained nurse, she had once correctly diagnosed a case of tonsillitis in me by spotting a tentative swallow. This skill became particularly useful during a stretch of hot summer weather when I was seven or eight years old. It was the late 1960s, and my family attended weekly Catholic mass in our suburban New Jersey town. After a string of stifling Sundays in the church — an upgrade to air conditioning was still a few years away — it became apparent that I was prone to fainting spells. Each week, about halfway through mass, I would begin to feel lightheaded. The full standing-to-kneeling repertoire of the Catholic service didn’t help matters. When my countenance crossed a certain threshold of paleness — recognizable only to my mother — she would skillfully steer me through the narrow pew, past my siblings and other parishioners toward a side exit, sparing me the embarrassment of public collapse.