Pentacles have been found in texts and grimoires from as early as the 15th and 14th centuries, and can still be found employed in magical rites today. Both bells and pentacles have been used as tools for protection for hundreds of years, with the bell being thought to purify negative energies from the air with its high-pitched sounds. Pentacles have been thought to invoke the power of the pentagram and the protection of the circle that encapsulates it.