Insular script was a medieval script system originally used in Ireland, then Great Britain, that spread to continental Europe under the influence of Irish Christianity. Irish missionaries also took the script to continental Europe, where they founded monasteries such as Bobbio. The scripts were also used in monasteries like Fulda, which were influenced by English missionaries. It is associated with Insular art, of which most surviving examples are illuminated manuscripts. It greatly influenced Irish orthography and modern Gaelic scripts in handwriting and typefaces.
The script developed in Ireland in the 7th century and was used as late as the 19th century, though its most flourishing period fell between 600 and 850. It was closely related to the uncial and half-uncial scripts, its immediate influences; the highest grade of Insular script is the majuscule Insular half-uncial, which is closely derived from Continental half-uncial script.
Works written in Insular scripts commonly use large initial letters surrounded by red ink dots (although this is also true of other scripts written in Ireland and England). Letters following a large initial at the start of a paragraph or section often gradually diminish in size as they are written across a line or a page, until the normal size is reached, which is called a "diminuendo" effect, and is a distinctive insular innovation, which later influenced Continental illumination style. Letters with ascenders (b, d, h, l, etc.) are written with triangular or wedge-shaped tops. The bows of letters such as b, d, p, and q are very wide. The script uses many ligatures and has many unique scribal abbreviations, along with many borrowings from Tironian notes.
Insular script was spread to England by the Hiberno-Scottish mission; previously, uncial script had been brought to England by Augustine of Canterbury. The influences of both scripts produced the Insular script system. Within this system, the palaeographer Julian Brown identified five grades, with decreasing formality:
- Insular half-uncial, or "Irish majuscule": the most formal; became reserved for rubrics (highlighted directions) and other displays after the 9th century.
- Insular hybrid minuscule: the most formal of the minuscules, came to be used for formal church books when use of the "Irish majuscule" diminished.
- Insular set minuscule
- Insular cursive minuscule
Insular current minuscule: the least formal; current here means ‘running’ (rapid).
Brown has also postulated two phases of development for this script, Phase II being mainly influenced by Roman Uncial examples, developed at Wearmouth-Jarrow and typified by the Lindisfarne Gospels.
Insular script was used not only for Latin religious books, but also for every other kind of book, including vernacular works. Examples include the Book of Kells, the Cathach of St. Columba, the Ambrosiana Orosius, the Durham Gospel Fragment, the Book of Durrow the Durham Gospels, the Echternach Gospels, the Lindisfarne Gospels, the Lichfield Gospels, the St. Gall Gospel Book, and the Book of Armagh.
Insular script was influential in the development of Carolingian minuscule in the scriptoria of the Carolingian empire.
In Ireland, Insular script was superseded in c. 850 by Late Celtic script; in England, it was followed by a form of Caroline minuscule.
The Tironian et (⁊) — equivalent of ampersand (&) — was in widespread use in the script (meaning agus ‘and’ in Irish and ond ‘and’ in Old English) and is occasionally continued in modern Gaelic typefaces derived from insular script.