In astrology, an arc is the difference on a chart between a progressed planet and the position of the planet on the natal chart. The Solar Arc is the most used form of this calculation.
Readers, please enjoy this guest blog post by Sandra Kynes, author of several books, including The Herb Gardener's Essential Guide, Plant Magic, and the new Witches' Encyclopedia of Magical Plants, among many others.
Although a few old books...