In the third book of the Roman mythological compendium, the Metamorphoses of Ovid, the poet tells how, before establishing the city of Thebes, Cadmus killed a rampaging dragon and sowed its teeth in the ground (Met. 3.50ff). From these teeth sprang armed men. No less lively and vigorously productive than the dragon’s teeth, John Milton declared sixteen centuries later, are books: “for books are not absolutely dead things, but do contain a potency of life in them to be as active as that soul whose progeny they are; nay, they do preserve as in a vial the purest efficacy and extraction of that living intellect that bred them” (Areopagitica).