Turing's 1936 paper on computable numbers hit that rare bull's eye where philosophy and discovery overlap. The mathematician Alonzo Church at Princeton came to the same findings just months before Turing. But unlike Church, who used the standard abstractions of pure mathematics in his argument, Turing wrote of machines, algorithms, ink, paper tape, and computation. (Before Turing, a "computer" referred not to a machine, but to a human being who calculated with paper and pencil.)