The Book of the Lady Catherine of Winchester
The Book of the Lady Catherine of Winchester is the only known work of Catherine of Winchester, and is one of only very few surviving books written by an Aureate magician. Written as it was by a practising magician - and one moreover who learned her magic at the feet of the King himself - The Book of the Lady Catherine of Winchester is unquestionably a book of magic.
Originally written in Latin, it was translated into English by Jane Tobias probably sometime in the early 19th century. It is likely that the copy from which she worked lay in the library of the house of Winter's Realm, in Grace Adieu, where she was employed as governess to two orphaned girls in the 1810s. It is unknown whether Gilbert Norrell possessed a copy of the book in his own library. Certainly he had no very high opinion of women as practitioners of magic, and moreover his dislike of all that is 'mystical' in relation to the subject is well-attested. On both grounds Lady Catherine's book might seem precisely the sort of work which would not tempt him. Nevertheless, so deep was Mr Norrell's love of books of magic, and so great his need to own copies of rare ones, that he may have stretched a point.
One passage from Tobias' translation indicates that the book presented a very typical medieval view of magic - that it magic closely associated with nature, and that it is not something which humans can ever entirely control, but can comply with [LoGA].
Above all remember this: that magic belongs as much to the heart as to the head and everything which is done, should be done from love or joy or righteous anger. . . .
This understanding is a gift to us from the Raven King, the dear king of all magicians, who stands between England and the Other Lands, between all wild creatures and the world of men [LoGA].