"It would be a very naive sort of dogmatism to assume that there exists an absolute reality of things which is the same for all living beings. Reality is not a unique and homogeneous thing; it is immensely diversified, having as many different schemes and patterns as there are different organisms. Every organism is, so to speak, a monadic being. It has a world of its own because it has an experience of its own. The phenomena that we find in the life of a certain biological species are not transferable to any other species. The experiences - and therefore the realities - of two different organisms are incommensurable with one another. In the world of a fly, says Uexkull, we find only "fly things"; in the world of a sea urchin we find only "sea urchin things."