"The similarity only holds to a point," Daniel cautioned him. "To avoid ambiguity, the Philosophic Language—Leibniz’s version of it, anyway—employs only prime numbers. In this, it is quite different from the number-lines of Descartes. In any case, the Language, as it consists of ideas and numbers, may be writ down using any scheme one may care to choose. The binary cypher of our Logic Mill is one such. But when I was a young man, John Wilkins devised another—the Real Character—which for a time was all the rage in the Royal Society. Hooke and Wren used it fluently."