‘What’s that?’ asked my husband, looking at my laptop. ‘Fibonacci fossilised?’ His question made no sense, but I saw what he meant. I was looking at a diagram of ‘the fabulous semantic engine, a sort of virtual sausage machine’ that I mentioned last week.

The diagram was circular, like a compass-rose with 37 points. Each point was connected to each of the others, like a church column to vaulting tracery. It is a metaphor map: the points represent categories for pigeonholing every word in English over the past 13 centuries. An underlying 415 semantic categories sort 793,742 word forms.

It is not like some delusion in which the secrets of the pyramids are transmitted mentally via television, but an analysis of the Historical Thesaurus derived from the Oxford English Dictionary. The Historical Thesaurus is the world’s first attempt at a comprehensive semantic classification of all words in the written record of a language. It was published as a book in 2009 and the project has been continued by Glasgow University, which published an edition online in 2020.

Very marvellous it is. The skeleton resembling Fibonacci spirals allows users to click on a category and see its connections with other categories metaphorically. Semantics, the science of meaning, depends on metaphor. When we say deep blue, deepness is a metaphor from three-dimensional space.

In identifying 10,000 metaphorical links between semantic categories, the Glasgow team ‘manually analysed’ four million word senses. Just click on their Metaphor Map and connections light up so you can read the details.

The Glasgow people suggest that ‘metaphorical connections can indicate how people mentally structure their world’. I’m not so sure, but it’s a project that would honour Aristotle, who divided up subjects and predicates into categories (in his work of that name). Such an undertaking is most familiar in the guise of Roget’s Thesaurus, but it formed part of John Wilkins’s attempt to construct a philosophical language in the 1660s.

The glory of today’s interactive Metaphor Map is that it embodies for an internet age the volvelles, little rotating dials, used in the works of Ramon Llull (1232-1315) to perform logical operations with combinations of semantic categories. It vindicates the art of that medieval Majorcan.