“Knocking on wood may not be magical, but superstition proved helpful in understanding why the ritual was effective. Across cultures, superstitions intended to reverse bad luck, like throwing salt or spitting, often share a common ingredient. In one way or another, they involve an avoidant action, one that exerts force away from oneself, as if pushing something away… This pushing action turns out to be important, because people’s beliefs are often influenced by bodily feelings and movements.”

—By Jane L. Risen and A. David Nussbaum, “Sense and Superstition” (via New York Times)