The assignment of genii to buildings and gates is connected with an important class of sacrifices; in order to provide a tutelary spirit, or to appease chthonic deities, it was often the custom to sacrifice a human being or an animal at the foundation of a building; sometimes we find a similar guardian provided for the frontier of a country or of a tribe.
A rationalistic explanation might be found in the connexion between the chthonic serpent and subterranean sources of wealth.3 Moreover, the serpent is often associated with metallurgy, and to serpent deities have been ascribed the working of metals, gem-cutting and indeed culture in general.
They were the guardianspirits of men and families, and stories are told of the way in which human life depended upon the safety of the reptile.'2 As a chthonic animal the serpent has often been regarded as an embodiment of the soul of the dead.
Among the Nayars of Malabar, the family-serpent is capable of almost unlimited powers for good or evil; it is part of the household property, but does not seem to be connected with ancestral cults.'4 In Greece, however, " the dead man became a chthonic daemon, potent for good or evil; his natural symbol as such, often figured on tombs, was the snake."
Apart from the more obvious characteristics of the serpent likely to impress all observant minds (§ 1), its essentially chthonic character shows itself markedly when it is associated with the treasures and healing herbs of the earth, the produce of the soil, the source of springs - and thence of all water - and the dust unto which all men return.'
