The method of obtaining fire requires considerable preparation of material and patience on the part of the operator. A pointed stick of hard wood is rubbed against a piece of dry paper-mulberry until a groove, is formed, which finally becomes hot from the friction and ignites the lint
or fiber thrown up at the end of the groove. This is blown into a flame, and dried grass added to it until the fire is sufficiently established. The difficulty of preserving suitable material in a perfectly dry state led to the custom of keeping up a perpetual fire in each community. These vestal fires were kept up by persons appointed for that purpose, though it does not appear that they were vestal virgins. Caves affording ample protection from the weather were selected for the location of these permanent fires, and although they had no religious significance, the flames were as carefully watched and attended as the celestial fire of the followers of Zoroaster.