But Touching Strangers, even when it alerts us to society’s hypocrisies, also does something more basic and more subtle: it brings us a reconsideration of the fundamental mystery of touch. Of the five traditional senses, touch is the only one that is reflexive: one can look without being seen, and hear without being heard, but to touch is to be touched. It is a sense that goes both ways: the sensitivity of one’s skin responds to and is responded to by the sensitivity of other people’s skin.

— Teju Cole, Known and Strange Things, Faber & Faber, Ch. Touching Strangers, 2016