The custom of the sacrifice of an animal, usually of a cock, on the foundations of a house but also references in popular tradition made to the sacrifice or the “building-in” of a human being, both done for the sake of of reinforcing, metaphorically, a building, are explained by a belief, common to many civilizations that the lifeless building and its surroundings obtain life through the sacrifice of a living creature. This happens because in traditional, pre-industrial civilizations the concept of space is qualitative and existential while in the industrial civilization it is quantitative and geometrically measured. The traditional man, a purely religious being ,seeks the sanctification of his dwelling where he will coexist with the divinity. Sanctification is achieved through the repetition and imitation of various deeds that god performed in some initial mythic time. The most important of these deeds is the Cosmogony, which almost in every religion is accompanied by a sacrifice. Therefore, the building of a house, as far as the religious, traditional man is concerned, must be a miniature of the Cosmogony, a belief and a need responsible for the above mentioned sacrifice.