Lexicographers have commented on how computer language borrows terms from carbon-based life activities to give binary computation a spurious physicality: handshake, lock-and-key and even the innocuous-looking homepage. (All of this anthropomorphism exists, as some critics darkly mutter, to soften us up for even more advanced states of social robotism.) But firewall is actually a scriptural concept for the nurture and protection of Jerusalem, as Zechariah tells us: ‘For I will be a wall of fire about it, says the Lord, and I will be the glory within it’ (Zechariah 2.5).

Much as I was surprised to learn that Ernst Jünger went into battle on the road to Cambrai with a copy of Laurence Sterne’s The Life and Opinions of Tristram Shandy in his map-case, I was even more surprised to read that Dwight ‘Ike’ Eisenhower kept a copy of Carlyle’s Sartor Resartus as his bedside reading during his years as Commander-in-Chief of Allied Forces, 1942 to 1945.

The Catalan writer Enrique Vila-Matas, in the latest of his novels, has a secret society of writers and artists, from Ramón Gómez to Marcel Duchamp, who all get together to shandy away. Goethe and Gogol would have to be among their number. But a secret society of sartorialists? Less likely, although Hitler’s last book was also by Carlyle: his biography of Frederick the Great.

Somebody once calculated that there are about 1400 pictures and diagrams in Wittgenstein’s writings, with which, of course, he sought to make clearer some ...