A moment’s distasteful thought will tell us that this could not be achieved by any creature, unless in possession of great wealth, considerable storage space and compliant neighbours.

Therefore, in reality, most goblins observe the Unggue Had – what one might term the common and lax form of Unggue – which encompasses earwax, finger and toenail clippings, and snot. Water, generally speaking, is reckoned as not unggue, but something which goes through the body without ever being part of it: they reason that there is no apparent difference in the water before and after, as it were (which sadly shines a light on the freshness of the water they encounter in their underground lairs). Similarly, faeces are considered to be food that has merely undergone a change of state. Surprisingly, teeth are of no interest to the goblins, who look on them as a type of fungus, and they appear to attach no importance to hair, of which, it has to be said, they seldom have very much.

At this point, Lord Vetinari, Patrician of Ankh-Morpork, stopped reading and stared at nothing. After a few seconds, nothing was eclipsed by the form of Drumknott, his secretary (who, it must be said, had spent a career turning himself into something as much like nothing as anything).

Drumknott said, ‘You look pensive, my lord,’ to which observation he appended a most delicate question mark, which gradually evaporated.

‘Awash with tears, Drumknott, awash with tears.’

Drumknott stopped dusting the impeccably shiny black lacquered desk. ‘Pastor Oats is a very persuasive writer, isn’t he, sir … ?’

‘Indeed he is, Drumknott, but the basic problem remains and it is this: humanity may come to terms with the dwarf, the troll and even the orc, terrifying though all these may have proved to be at times, and you know why this is, Drumknott?’