Holmes smiled as he turned up an entry in his note-book.

"I spent a morning in the British Museum reading up on that and
other points. Here is a quotation from Eckermann's Voodooism and
the Negroid Religions:

"'The true voodoo-worshipper attempts nothing of importance
without certain sacrifices which are intended to propitiate his
unclean gods. In extreme cases these rites take the form of
human sacrifices followed by cannibalism. The more usual victims
are a white cock, which is plucked in pieces alive, or a black
goat, whose throat is cut and body burned.'

"So you see our savage friend was very orthodox in his ritual.
It is grotesque, Watson," Holmes added, as he slowly fastened his
notebook, "but, as I have had occasion to remark, there is but
one step from the grotesque to the horrible."