Magic at the Inbetween Places
In a world so shifting and uncertain, it is not surprising that great store was set on all things that were not clearly one thing or another. At the inbetween places—rivers and borders—and at all edges, verges, brinks, rims, fringes, and dividers, anything might happen, and chaos could be loosed upon the world. It made no difference whether these were borders of space or of time. Caves, the thresholds between open air and the solidity of earth, were often entrances to the world of spirits. Wells linked the visible world with subterranean realms and had an innate enchantment that might give awareness of the future or restore the dead to life. In the space dividing foam and water or bark and tree, devils could be confined by those who knew how. Dawn and dusk were magical times, for they divided the fundamental elements of existence: night from day, darkness from light, the period when evil was abroad from the time when it was banished to its secret sanctuaries.
— Time-Life Books, Wizards and Witches, p. 12