The interlaced knot, thread passing over and under thread in a line that folds back on itself, is one of the most recognisable visual motifs in the world. It is on standing stones, on manuscripts, on metalwork, on tattoos and jewellery, and it has become a primary visual shorthand for "Celtic" anywhere in the world.

Like tartan, it has been vulgarised by repetition and misunderstood in the process, reduced to a style element cut loose from its original context.

That original context is the manuscript and metalwork tradition produced in Ireland, Scotland and Northumbria between roughly the sixth and ninth centuries. The Book of Kells, the Lindisfarne Gospels, the Book of Durrow and the Tara Brooch represent a standard of design invention and technical execution that is, in my view, unsurpassed in the fifteen centuries since. That is a judgement rather than a fact, and I am comfortable defending it.

One correction before anything else. This is not Scotland's visual language. It is a shared tradition of Ireland, western Scotland and Northumbria, and its two greatest surviving monuments are held in Dublin and London. Scotland's share in it is real and substantial. It is a share.

The Insular tradition

Insular art is the term scholars use for the visual tradition that emerged in the monasteries of Ireland and Scotland in the sixth century and spread through the monastic network to Ì Chaluim Chille (EE CHAL-im CHILL-uh), Iona, to Lindisfarne, to Northumbria and beyond. It is insular, meaning of the islands, because it developed in the Atlantic archipelago in relative isolation from the dominant Late Antique and Byzantine traditions and evolved its own vocabulary.

It draws on several sources woven into something new:

Pre-Christian Celtic metalwork. The curvilinear spirals and trumpet shapes of La Tène style, on the Battersea Shield, the Desborough Mirror and the great Iron Age torcs, supplying the basic vocabulary of formal complexity.

Pictish stone carving. The precise, energetic symbol art of eastern Scotland, contributing dense and formally charged composition.

Late Antique and Mediterranean sources, supplying the manuscript format and elements of the ornamental canon, with the carpet-page concept possibly reaching the islands through Coptic Christian contact.

Germanic animal ornament. Style II interlace, of the kind seen at Sutton Hoo, which is East Anglian rather than Insular and which fed into the tradition rather than belonging to it.

What the Insular workshops did with these was not eclectic but synthetic. They made a genuinely new visual language in which interlace, zoomorphic entanglement, spiral ornament and the sacred text were integrated into a single experience.

The grammar

Knotwork is not random interlacing. It follows rules, and knowing them turns looking at it from appreciation into comprehension.

The grid. Knotwork is constructed on a grid, square or diagonal, laid out first as a field of dots or intersections and then connected into bands by a defined procedure.

Over-under alternation. At every crossing the thread alternates between passing over and passing under. This single rule, applied consistently, produces the characteristic depth: the sense that the bands are physically interlaced rather than drawn flat. Breaking it anywhere is immediately visible and is the commonest fault in modern imitations.

Continuity, with a caveat. You will very often read that a true Celtic knot is a single unbroken line without beginning or end, and that this is the source of its meaning.

Some Insular knotwork is single-strand. A great deal of it is not. Many panels use two, three or more independent strands, and the corpus is formally far more varied than the endless-line reading allows. The claim that following any line in any correct knotwork will take you over and under every crossing before returning to the start is simply not true as a general statement.

The endless knot is a real formal possibility and a beautiful one. It is not the definition of the form, and the devotional gloss attached to it is largely modern.

Zoomorphic interlace. The most distinctive Insular move: threads that become animals. Birds, serpents, dogs and fantastic creatures whose bodies elongate into bands and whose tails and tongues become interlaced elements, simultaneously legible as creature and as pattern. Maintaining the interlace rules while managing zoomorphic content across a page-sized composition is a feat of design that is worth sitting with.

Iona and the Book of Kells

The Book of Kells, held at Trinity College Dublin since the seventeenth century, is attributed by many scholars to the scriptorium at Iona. The attribution is disputed, with arguments also made for Kells in County Meath and for a shared production, and the honest position is that we do not know.

If Iona is right, one of the most ambitious works of art in the history of Christianity was made in a small Hebridean island monastery, in the Atlantic light, with pigments traded across the known world: lapis lazuli from Afghanistan for the deep blue, verdigris from oxidised copper for the greens, red lead for the vermilion, orpiment, which is arsenic sulphide, for the yellows.

The Chi Rho page, opening the account of Christ's birth with the abbreviated Greek name, is the page most reproduced: a dense composition of knotwork, zoomorphic interlace and spiral that rewards hours of looking.

And in among it, at the foot, a small joke. Two cats sit watching two mice or rats nibbling at a eucharistic host. An otter with a fish appears nearby, and moths in the negative spaces. The domestic world of a working monastery, complete with its vermin problem, inserted into the sacred text.

You will sometimes read that the moths signify the soul. There is no support for that in the Insular material. It is a modern reading and I would leave it as an open question, which is more interesting anyway.

Pictish carving

The carved stones of the Picts, Na Cruithne (nuh KROO-nyuh), are a related but distinct tradition: carved rather than painted, public rather than private, and using a symbol system that remains undeciphered. The formal qualities are related to the manuscripts, with the same love of interlace, the same precision, the same combination of abstract geometry with zoomorphic imagery.

The Aberlemno kirkyard stone is the best-known example of the combination: an elaborate ringed cross on one face, a battle scene and Pictish symbols on the other. Two visual vocabularies coexisting on one stone without apparent conflict.

The Pictish material has its own article on this site, including the honest position on what the symbols mean, which is that we do not know.

The modern practice, and where it came from

Here is the part the popular accounts leave out, and it is the most interesting thing in the subject.

There is no unbroken tradition of knotwork construction. The methods were lost. What exists today is a reconstruction, and we know exactly who made it.

George Bain, an art teacher working in Kirkcaldy, spent decades analysing Insular manuscripts and carvings and working out from first principles how the patterns had been built. He published Celtic Art: The Methods of Construction in 1951. His son Iain Bain extended the work in 1986. Between them they are the source of every grid-and-rules construction method taught anywhere today.

Before Bain there was the Victorian Celtic Revival, which produced an enormous quantity of Celtic-styled ornament without much understanding of how the originals were made, and which is the actual ancestor of most "Celtic" design in circulation.

So the honest lineage is: Insular workshops, sixth to ninth centuries. A gap of a thousand years. Victorian revival. Bain's reconstruction, 1951. Everything since.

That does not diminish the practice. Bain's achievement was extraordinary and the methods work. But it means that when you draw a knot you are doing something twentieth century in origin, built by careful scholarship on a genuine ancient body of work, and that is a different claim from unbroken descent.

Drawing it

The practice is not merely technical. Holding the over-under rule at every crossing, keeping the strands coherent, managing the relationship between the part and the whole across a complex field, produces a quality of attention that practitioners consistently describe as meditative. You cannot think about anything else while constructing knotwork correctly. The form demands presence.

Whether the Insular monks experienced it that way we cannot know. That they were making objects whose making was itself a discipline seems, from the evidence of the pages, difficult to doubt.

A note on the Gaelic: an earlier version of this article carried several terms I could not verify, including one which turned out to mean "Indian" rather than "insular". They have been removed. Only terms confirmed against Am Faclair Beag remain. Corrections welcome.

Sources

  • Bain, G. (1951). Celtic Art: The Methods of Construction. Republished by Constable and by Dover. The foundation of all modern knotwork practice.
  • Bain, I. (1986). Celtic Knotwork. Constable.
  • Meehan, B. (2012). The Book of Kells. Thames & Hudson. The standard accessible account, by the manuscript's curator at Trinity College Dublin.
  • The Book of Kells online. Trinity College Dublin have digitised it in full, free, at high resolution. The Chi Rho page is folio 34r.
  • Henderson, G. & Henderson, I. (2004). The Art of the Picts. Thames & Hudson.
  • Youngs, S. (ed.) (1989). The Work of Angels: Masterpieces of Celtic Metalwork. British Museum Press.
  • Backhouse, J. (1981). The Lindisfarne Gospels. Phaidon.
  • On the Victorian Celtic Revival and the invention of Celtic visual identity, see Trevor-Roper in Hobsbawm & Ranger (eds.), The Invention of Tradition, Cambridge University Press, 1983.
  • Am Faclair Beag for the Gaelic.

Related: [The Pictish Stones]; [Ogham]; [Tartan: Scotland's Colour Code]; [How to Read an Esoteric Claim]