This week Facebook announced that it was to launch a new cryptocurrency, a form of digital money aimed at hoovering up profits from people in developing countries without access to banks – or, as Mark Zuckerberg put it more subtly: “I believe it should be as easy to send money to someone as it is to send a photo.”

The ancient Greek root kryptos (from which we get “crypt”) means concealed or secret. So an animal might be a cryptodont (lacking obvious teeth), and a politician might be a crypto-fascist. Cryptography is “secret writing”, or coded communication – as with the German Enigma machine, or encrypted messaging services. And cryptocurrency (such as Bitcoin) is digital coinage that uses cryptographical techniques for secure transactions.

Facebook calls its new cryptocurrency the Libra, which was the Roman word for “scales” or “balance” and also a unit of weight. So the modern pound is abbreviated “lb”, and the star sign Libra holds the scales of justice. And, given its record on privacy, users might wonder just how long their cryptocurrency transactions will remain safe from prying eyes.