Now, in order to understand clearly how this necessity of getting rid of hostile spirits came to suggest those solemn processional rites which we associate with the word _lustratio_, we must fully appreciate the fact that the earliest settlers in Italy who had any knowledge of agriculture found it a country of forest-clad hills; the river valleys were marshy and unhealthy, and the earliest settlements were in clearings made in the woodland. This fact was dimly appreciated by the Romans themselves, and is proved by the archaeological evidence available to-day. The first thing, then, to be done was to make a clearing; and this was a most perilous task, for when you cut down trees and dug up the soil, how were you to tell what unknown spirits you might be disturbing and aggravating? They might be in the trees and the plants, they might be in the animals whose homes were in the trees and the ground, the rocks and the springs. In the later Roman ritual we can still see traces of this old feeling of peril. Cato has preserved for us the formula used by the farmer in historical times when making a new clearing; the prayer accompanying his sacrifice began with ‘Si deus, si dea’--for how was he to know the name or sex of the spirit of the wood he was invading? When digging up the soil he had to offer an expiatory sacrifice; and the ancient gild of the Fratres Arvales had to offer special _piacula_ for the falling of a bough in their grove, or for any injury to a tree in it.[119] And when your clearing was complete, and you had settled down with your own household spirits, e. g. of the hearth-fire and the store-cupboard (Vesta and Penates), or had induced some of the native spirits to be friendly and serviceable to you--those especially of the land and the springs,--there was yet another difficulty of the greatest importance, viz. to keep those wild ones still dwelling in the woodland around you from encroaching on your clearing or annoying you in your dwelling. That they really could be thus annoying is proved by a curious bit of folklore of which Varro knew, and which has luckily been preserved by St. Augustine, a student of Varro’s works, as an example of Pagan absurdity (_Civ. Dei_, vi. 9). After the birth of a child, three spirits were invoked--Intercidona, Pilumnus, and Deverra--to prevent Silvanus (the later representative of the woodland spirits generally) from coming into the house and making mischief by night. These three spirits, as their names show, represented the life of settled agriculture: the cutting and pruning of trees (Intercidona), the pounding of corn for the daily meal (Pilumnus), and the raking and sweeping up of the grain (Deverra); and Varro says that they were represented by three men, who imitated the action of axe, pestle, and broom. The real significance of this delightful bit of mummery has never, I think, been correctly understood, simply because the vital