"... Anthropologists always dealt with dietary rules using different approaches and providing various explanations: I will provide here just a brief overview of the main theories developed in recent years, with their leading figures. Lévi-Strauss regarded food taboos as a sort of feedback effect originating from the semantic categorization that, according to his theoretical system, is used by each human society to organize natural phenomena. Taboos, thus, prohibit the consumption of animals which do not precisely fit into such binary category system. Similarly, Leach acknowledged prohibitions and rules as determined by the discriminating grids with which men classify the world they know, particularly through language: taboo is, thus, everything that is a “non-thing” among given and determined names. Also Douglas considered food avoidances as a matter of classification of the world, but in addition she combined to such issue the concept of “dirty”: when coming to the matter of biblical taboos, animals would thus be classified according to degrees of purity, which depend, in their turn, on their behavior within the three natural spheres of land, air, and water ..."