E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
A five-sided head-dress of fine linen, meant to represent the five senses, and worn as a defence against demons in the act of conjuration. It is also called Solomons Seal (signum Salamonis). A pentacle was extended by the magician towards the spirits when they proved contumacious.
And on her head, lest spirits should invade,
A pentacle, for more assurance, laid.
Rose: Orlando Furioso, iii. 21.
The Holy Pentacles numbered forty-four, of which seven were consecrated to each of the planets Saturn, Jupiter, Mars, and the Sun; five to both Venus and Mercury: and six to the Moon. The divers figures were enclosed in a double circle, containing the name of God in Hebrew, and other mystical words.