Custom, which precedes all laws, originally gave rise to them. For legislators who are concerned with the ordinary affairs of life, carefully examining everything separately, established rules in accordance with the requirements of Nature. Therefore, since these matters relating to the common concerns of life (as We have already stated) give occasion for the birth of laws, and where a case which was provided for by the ancient enactments presents itself, it becomes necessary to formulate a new rule, so that when there is need of it, a legal decision may be rendered in accordance with circumstances: We are about to enact the following law. And what is the character of this law? Where two fields are contiguous, and belong to different owners, one of them being situated upon an elevated spot, and the other lower down, and part of the upper field, either with or without trees, becomes detached and covers the lower tract, the owner of the latter can not absolutely and unceremoniously appropriate the soil which has slipped down, nor can the owner of the other tract extend the boundaries of the same to the point to which his own ground has been carried, but the former will be compelled to permit the latter to remove the soil if he desires to do so, no matter whether it contains trees or not, so that he will have an opportunity to recover the soil if he wishes to take it back to its original place, or to renounce all right to it if he does not desire to do this, by abstaining from any claim to the tract on which it was deposited, and in no way prejudicing the title of the owner of this land. Again, where two houses are adjacent, and one of them is higher than the other, and the latter falls upon the former, the owner of the first house can remove his materials, and, if he does not do so, they shall be lost, so far as his rights to them is concerned, nor can he annoy the owner of the second building on account of them. This is the rule which should be observed in cases of this kind.