Polyface Farm is built on the efficiencies that come from mimicking relationships found in nature and layering one farm enterprise over another on the same base of land. In effect, Joel is farming in time as well as space - in four dimensions rather than three. . .The ides is not to slavishly imitate nature, but to model a natural ecosystem in all its diversity and interdependence, one where all the species 'fully express their physiological distinctiveness'. He takes advantage of each species' natural proclivities in a way that benefits not only the animal but other species as well.