Newton responded in kind. "Of every lot of coins that is minted, some are plucked out, and deposited. I shall demonstrate, behold!" Newton opened his own coin-purse and spilled a guinea and some pennies—freshly minted, of course—onto his hand. He borrowed a sheet of foolscap from a clerk, laid it on the Pyx, arranged the coins in the center of the page, and then rolled and folded the paper around the money to make a neat little packet. "Here I have done it with paper—at the Mint we use leather. The Sinthia, as we call this little packet, is sewn shut. The worker writes on its outside a notation as to when the sample was taken, and stamps it with a seal, kept for that purpose alone. Then—" Sir Isaac slipped the Sinthia into the Pyx’s hatch, and tripped the mechanism. It vanished and dropped within.