Knots in the Nursery: (Cats) Cradle Song of James Clerk Maxwell

A field of mathematics can acquire energy from a notable paper. I will wager that knot theory is the only field that was both propelled by a paper and heralded by a poem. The paper, “On knots,” was written by the Scottish mathematician and physicist Peter Guthrie Tait in 1877. The poem, (Cats) Cradle Song, was a witty response by James Clerk Maxwell, another Scottish mathematician as well as a physicist, who today ranks alongside Newton and Einstein. Many associate Maxwell only with the eponymous equations that relate electricity and magnetism. Sadly, scientists are seldom remembered for their general intellect or sense of humor.1 Maxwell’s writing reveals an abundance of both. Tracing Maxwell’s literary influences is trickier than chasing down his scientific ones. Maxwell’s biographer, Lewis Campbell, boasts of his subject’s wide-ranging tastes in literature: “[Maxwell’s] acquaintance not only with scientific literature, but with nearly every other class of books was astonishing.” Lewis Carroll was among Maxwell’s favorite authors.2 Maxwell’s enjoyment of books was matched by his obsession with puns. They were more than exercises for his sprinting mind. In a Cambridge essay of 1858, Maxwell explained: