An ABC of Witchcraft Past and Present - Doreen Valiente 2018
Book of Shadows
This is the name given by modern witches to the book in which they write their rituals, invocations and charms. Witches copy from each others’ books that which appeals to them, and things which have been learned from experience; so that in practice no two books are exactly alike.
An old rule of the covens, with regard to written material of this description, is that when anyone died his book was to be burned. (See WITCHCRAFT.) The reason for this, from the old days, was to save embarrassment to the person’s family. A written book was proof positive to accuse a person of witchcraft; and as the latter was popularly supposed to run in families, the discovery of such a thing might make the position of a witch’s surviving relatives very difficult.
Such a writing is called a Book of Shadows, because its contents can only be this world’s shadow of the realities of the Other World; the world of magic and the Beyond, the world of gods and spirits. Even so, I am told, do Freemasons regard their ceremonies; which they preserve “until time and circumstance shall restore the great originals”.