By Mr. Robert Kirk, Minister of Aberfoyle, 1691.
The Siths, or Fairies, they call Sluagh Maith, or the Goodpeople, it would seem, to prevent the dint of their ill attempts (for the Irish used to bless all they fear harm of), and are said to be of a middle nature betwixt man and angel, as were demons thought to be of old, of intelligent studious spirits, and light changeable bodies (like those called astral), somewhat of the nature of a condensed cloud, and best seen in twilight. These bodies be so pliable through the subtlety of the spirits that agitate them, that they can make them appear or disappear at pleasure. Some have bodies or vehicles so spongeous, thin, and defecat [pure] that they are fed by only sucking into some fine spirituous liquors, that pierce like pure air and oil; others feed more gross on the foyson [abundance] or substance of corn and liquors, or corn itself that grows on the surface of the earth, which these fairies steal away, partly invisible, partly preying on the grain, as do crows and mice; wherefore in this same age they are sometimes heard to break bread, strike hammers, and to do such like services within the little hillocks they most do haunt; some whereof of old, before the Gospel dispelled Paganism, and in some barbarous places as yet, enter houses after all are at rest, and set the kitchens in order, cleansing all the vessels. Such drags go under the name of Brownies. When we have plenty, they have scarcity at their homes; and, on the contrary (for they are not empowered to catch as much prey everywhere as they please), their robberies, notwithstanding, ofttimes occasion great ricks of corn not to bleed so well (as they call it), or prove so copious by very far as was expected by the owner.
Their bodies of congealed air are sometimes carried aloft, other whiles grovel in different shapes, and enter into any cranny or clift of the earth where air enters, to their ordinary dwellings; the earth being full of cavities and cells, and there being no place, no creature, but is supposed to have other animals (greater or lesser) living in or upon it as inhabitants; and no such thing as a pure wilderness in the whole universe.