The earliest surviving substantive illuminated manuscripts are from the period AD 400 to 600, primarily produced in Ireland, Italy and other locations on the European continent. The meaning of these works lies not only in their inherent art history value, but in the maintenance of a link of literacy. Had it not been for the (mostly monastic) scribes of late antiquity, the entire content of western heritage literature from Greece and Rome could have perished. The very existence of illuminated manuscripts as a way of giving stature and commemoration to ancient documents may have been largely responsible for their preservation in an era when barbarian hordes had overrun continental Europe.

The majority of surviving manuscripts are from the Middle Ages, although many illuminated manuscripts survive from the 15th century Renaissance, along with a very limited number from late antiquity. The majority of these manuscripts are of a religious nature. However, especially from 13th century onward, an increasing number of secular texts were illuminated. Most illuminated manuscripts were created as codices, although many illuminated manuscripts were rolls or single sheets. A very few illuminated manuscript fragments survive on papyrus. Most medieval manuscripts, illuminated or not, were written on parchment (most commonly calf, sheep, or goat skin) or vellum (calf skin). Beginning in the late Middle Ages manuscripts began to be produced on paper.

Illuminated manuscripts are the most common item to survive from the Middle Ages. They are also the best surviving specimens of medieval painting. Indeed, for many areas and time periods, they are the only surviving examples of painting.

The Scriptorium
A scriptorium (plural scriptoria) was a room devoted to the hand-lettered copying of manuscripts. Before the invention of printing by moveable type, a scriptorium was a normal adjunct to a library. In the monasteries, the scriptorium was a room, rarely a building, set apart for the professional copying of manuscripts. The director of a monastic scriptorium was the armarius or scrittori, who provided the scribes with their materials and directed the process. Rubrics and illuminations were added by a separate class of specialists.

Techniques
Illumination was a complex and frequently costly process. As such, it was usually reserved for special books: an altar Bible, for example. Wealthy people often had richly illuminated "books of hours" made, which set down prayers appropriate for various times in the liturgical day.

Papyrus, the writing surface of choice in Antiquity, became prohibitively expensive as commercial supplies dried up propably through over-harvesting (see Papyrus) and was replaced by parchment and vellum. During the 7th through the 9th centuries, many earlier parchment manuscripts were scrubbed and scoured to be ready for rewriting. Such overwritten parchment manuscripts, where the original text has begun faintly to show through, are called palimpsests. Many of the works of Antiquity often said to have been preserved in the monasteries were only preserved as palimsests. In the 13th century paper began to displace parchment. As paper became cheaper, parchment was reserved for elite uses of documents that were of particular importance.

In the making of an illuminated manuscript, the text was usually written first. Sheets of parchment or vellum, animal hides specially prepared for writing, were cut down to the appropriate size. After the general layout of the page was planned (e.g., initial capital, borders), the page was lightly ruled with a pointed stick, and the scribe went to work with ink-pot and either sharpened quill feather or reed pen.

The script depended on local customs and tastes. The sturdy Roman letters of the early Middle Ages gradually gave way to cursive scripts such as Uncial and half-Uncial, especially in the British Isles, where distinctive scripts such as insular majuscule and insular minuscule developed. Stocky, richly textured blackletter was first seen around the 13th century and was particularly popular in the later Middle Ages.

When the text was complete, the illustrator set to work. Complex designs were planned out beforehand, probably on wax tablets, the sketch pad of the era. The design was then traced onto the vellum (possibly with the aid of pinpricks or other markings, as in the case of the Lindisfarne Gospels).

Classifications
Art historians classify illuminated manuscripts into their historic periods and types, including (but not limited to): Insular script, Carolingian manuscripts, Ottonian manuscripts, Romanesque manuscripts and Gothic manuscripts.

Insular/Celtic Manuscripts
The term insular is used to refer to manuscripts produced in monastic centres in the British Isles in the seventh and eighth centuries. Insular manuscripts were written in uncial or half uncial scripts and were the first manuscripts to introduce spaces between words to make it easier to read. They were decorated in abstract linear patterns adapted from Anglo-Saxon and Celtic metalwork and where zoomorphic forms were included these were stylised and either copied from earlier art or drawn from the imagination. Three forms of decoration are commonly found in insular manuscripts: ornamented borders enclosing full page illustrations; ornate initials used for beginning of gospels and important passages; and carpet pages, which are full pages of decorative designs. Well known examples of Insular manuscripts are the Lindisfarne Gospels (c.698AD), the Book of Durrow (c.680AD) and the Book of Kells (c.800AD).

The Book of Kells, Ireland, A.D. 800

The Book of Durrow, Ireland, 7th century

The Book of Lindisfarne, England, late 7th or early 8th century

The Codex Aureus, England, 9th century

Ottonian manuscripts
The Ottonian style is associated with the courts of the Saxon emperors from 960-1060. Gospel books, pericopes (books of Gospel readings) and the Apocolypse were more popular than entire bibles. Ottonian manuscripts were influenced by Byzantium, featuring the use of burnished gold backgrounds and large eyed figures in rigid, hieratic poses.

Ottonian manuscripts, Germany, 10th and 11th centuries

Carolingian manuscripts
The Carolingian style is associate with the court of Charlemagne who set out to revive book design and production. Manuscripts during this period were made for imperial and aristocratic use as well as for ecclesiastical use and it was at this time that manuscript production expanded from the monasteries to secular workshops. Caroline manuscripts were written in Caroline miniscule text and were more classical in style. They sometimes included sections written in gold or silver ink on purple vellum and often contained lavish quantities of gold. The illuminations were display a combination of two dimensional ornament and increased sense of three dimensions in the depiction of figures. The Old Testament was a popular subject popular because its political themes appealed to a courtly audience. One of the best-known, but not typical, Carolingian mansucripts is the Utrecht Psalter (c.820-830AD)

Further reading and images
http://members.tripod.com/bibliomane/utrecht_psalter.htm
http://psalter.library.uu.nl/

Carolingian manuscripts, France, 7th to 10th centuries

Romanesque manuscripts
The Romanesque style, which dates from the year 1000, was an international rather than a national style and examples of Romanesque manuscripts come from a wide geographical area. During this period a wider variety of books was produced, including large Bibles and commentaries, lives of Saints, theological works, missals and Psalters as well as Gospels. An increase in monasticism meant that many books were produced for public use, leading to the production of larger sized books. Romanesque manuscripts feature grotesques (a variety of real and imaginary creatures), textured or gold backgrounds, and historiated initials. These initials, found at the commencement of a chapter, combined the initial of the opening word with foliage, figures or pictures illustrating a portion of the text. These initials, which were more common than full-page illustrations, could sometimes extend the length of the page. One well-known example of a Romanesque manuscript is the Winchester Bible (c.1150-1200AD)

The St.Albans Psalter, England, 12th century

Gothic Manuscripts
The Gothic style dates from around 1150AD and, like the Romanesque, was an international style. The rise of universities and cathedral schools led to an increased demand for books of all kinds. During the Gothic period books became smaller and more delicate, with increased integration between illustrations and text. Generally there was less text on page, with blank spaces in lines of text being filled with decorative bars. Illustrations were sometimes combined with borders, and marginal sketches and grotesques (now known as drolleries) were reintroduced. Historiated initials were reduced in size, but illustrations, known as bas de page, were included at the bottom of text pages. Decorative scrolls of ivy leaves were a feature of many Gothic manuscripts. The mid fourteenth century saw the introduction of original illustrations. Previously text was copied from book to book and so were illustrations (modified of course to suit changing tastes), leading to continuity in iconography. However from mid-fourteenth century some illustrators were making their own images, which became increasingly naturalistic. Famous Gothic manuscripts include the works the Limbourg Brothers produced in the fifteenth century for the Duc de Berry.

Gothic book pages from the 13th century

Gothic book pages from the 14th century. Second from left: The Fitz-Payne Book, second from right the Queen Mary Psalter.

Gothic book pages from the 15th century, from France, Italy and Hungary.

The Chronicles of Hainaut. France, 15th century

The Book of Hours
A Book of Hours is the most common type of surviving medieval illuminated manuscript. Each Book of Hours is unique, but all contain a collection of texts, prayers and psalms, along with appropriate illustrations, to form a convenient reference for Christian worship and devotion. The Books of Hours were composed for use by lay people who wished to incorporate elements of monasticism into their devotional life. Reciting the hours typically centered upon the recitation or singing of a number of psalms, accompanied by set prayers. The most famous of these were created by the Limbourg Brothers for the Duc de Berry at the beginning of the 15th century.

Books of Hours for the Duc de Berry. Top: Les Tres belles Heures du Duc de Berry, bottom: Les Tres Riches Heures du Duc de Berry.

However Books of Hours were not limited to the Duc de Berry's library. Here are a few more samples from the 15th and 16th centuries:

Books of Hours from France and the Netherlands. 15th and 16th centuries

Music scores (antiphoner) from late Gothic times.

Initials and Diminuendo
In Typography diminuendo is the art of arranging letters starting with a large initial and progressively diminishing the point size of the type as it runs into the body text, assuring a smooth transitio between initial and body text. Possibly the most captivating design features of illuminated manuscripts are these initials and the diminuendo, both of which are widely implemented in contemporary editorial design today as well:

Initials and Diminuendo

As Medieval Europe metamorphosed into a new age through the Renaisance these beautiful hand crafted books inevitably gave way to the onset of a new technology: The printing press, whereby books could be mass produced and became everyday objects of use rather than the jewels hidden in the libraries of Popes, Dukes and Kings as they had been for many many centuries. However, as we shall see in the next section, the change was gradual and although the beauty of the illuminated manuscript was forever lost another beauty came to replace it: The mastery of the grid and of type.

Furher reading and images
http://www.abdn.ac.uk/stalbanspsalter/english/index.shtml
http://www.ceu.hu/medstud/manual/MMM/index.html
http://www.wga.hu/
http://www.kb.nl/kb/manuscripts/
http://www.bodley.ox.ac.uk/dept/scwmss/wmss/medieval/browse.htm
http://www.museumhetvalkhof.nl/gebroedersvanlimburg/content/persdui.htm
http://www.medieval-life.net/index.htm

References
http://en.wikipedia.org/wiki/Illuminated_manuscript
http://en.wikipedia.org/wiki/Scriptorium
http://www.csu.edu.au/faculty/arts/humss/art317/manstyles.htm