I found it to be a curious ring, made of some greying material. The curious thing about it was that it was made in the form of a pentagon; that is, the same shape as the inside of the magic pentacle, but without the "mounts" which form the points of the defensive star. [...] It was whilst I stood there, looking at the ring, that I got an idea. Supposing that it were, in a way, a doorway – you see what I mean? A sort of gap in the world-hedge, if I may so phrase my idea. [...] Then the shape – the inside of a pentacle. It had no "mounts", and without the mounts, as the Sigsand manuscript has it: "Thee mownts wych are thee Five Hills of safetie. To lack is to gyve pow'r to thee daemon; and surlie to fayvour thee Evill Thynge."
found in W H Hodgson's Carnacki the Ghost Finder (1913)