perspectives of interpretation, both of which are equally well justified by the actual facts, The situation in biology should be no different than we have found it in physics, although in biology the difference between the two viewpoints has assumed far sharper outlines, In any case, we may say in summary that ac- cording to what exact natural science teaches us, the entire realm of nature, in which we human beings on our tiny mote of a planet play only an infinitesimally smalls part, is ruled by definite Jaws which are independent of the existence of thinking human beings; but these laws, insofar as they can at all be comprehended by our senses, can be given a formulation which is adapted for purposeful activity, Thus, natural science ex: hibits a rational world order to which nature and mankind are subject, but x world order the inner ‘essence of which is and remains unknowable to us, since only our sense data (which can never be completely excluded) supply evidence for it, Nevertheless, the truly prolific results of natural- scientific research justify the conclusion that con- tinuing efforts will at least keep bringing us pro- gressively nearer to the innttainable goal, and