Given that this is the topic to which I have dedicated the last five years of my life, I may be giving something of a biased view, but to be honest I cannot think of a more fascinating facet of Anglo-Saxon society. The most sophisticated medical text ever produced in the Old English language is known as the Leechbook of Bald. The text is fascinating because it sheds light on how the Anglo-Saxons viewed the human body and the causes of illness. But perhaps more interesting is that the text seems to have been translated from a range of medical texts in Latin, which ultimately derive from authorities such as Alexander of Tralles, Oribasius, Celsus, Marcellus, Caelius Aurelius and pseduo-Galen. Basically, this is a roll-call of the best medical authors available from antiquity. (See Cameron's Anglo-Saxon Medicine for more details).
Ultimately I hope to show that the Old English medical authors read and comprehended the best of the medical classics available in their day, and brought them up to date in a coherent and consistent fashion. To them, disease was caused by an imbalance of the four humours (þa feower wætan in Old English): blood, phlegm, red (or yellow) bile, and black bile, an idea ultimately derived from Hippocrates. Imbalances of the four humours were treated by the application of remedies of the opposite property, so excessive cold dampness, such as an excess of plegm, would be prescribed pepper which is hot and dry.
Bald's Leechbook, in BL MS Harley 55 (image from www.historyofscience.com)
To demonstrate this more fully I am sifting through the Latin medical literature of the early middle ages, and trying to demonstrate exactly how much of the Leechbook of Bald was translated from this enormous canon, in an effort to demonstrate how the compiler was working. After that, I am examining exactly how the translators went about the difficult business of translating rather technical Latin terms into Old English; let's face it, doctors have been using incomprehensible jargon since the dawn of time.
For example, the second Leechbook of Bald has seven chapters on the liver alone (Book II, chapters 17-24). These begin by describing the structure of the liver, roughly paraphrasing a chapter from a fourth-century anatomical work by Helvius Vindicianus known as the Epitome altera. Then, everything that can possibly go wrong with the liver is listed according to the scheme laid out by the pseudo-Galenic Liber tertius. Then for the remaining six chapters there is an alternation between the diseases and cures described in the Liber terius and those described by Alexander of Tralles, so that the Anglo-Saxon compiler has effectively covered every angle.
What is so exciting about this is that it demonstrates the availability of Greek medical texts in Latin translation as far west as England as early as the tenth century, whereas the standard histories of medicine seem to operate under the assumption that there was virtually no Greek medicine in the West until Constantine the African (d. 1090) began translating Arabic medicine in Latin in the eleventh century at the abbey of Montecassino.