But let us now leave Positivism and continue with our own train of thought. The law of the conservation of energy is, after all, not the only law of nature, it is just one among many, While ic is true that it is universally valid, it is still not sufficient for predicting every detail of a natural process, since it leaves an endless number of possi- bilities still open. But there is another, far broader law, which has the property of giving a specific, unequivocal answer to each and every sensible question con- cerning the course of a natural process; as far as we can see, this Inw—like the law of the conserva- tion of energy—possesses an exact validity even for the most modern parts of physics. But what ‘we must regard as the greatest wonder of all, is the fact that the most adequate formulation of this law creates the impression in every unbiased ‘mind that nature is ruled by a rational, purposive will, Let me illustrate this by a specific example, Ic is a well known fact that when a ray of light strikes the surface of a transparent body obliquely, such as the surface of water, it is deflected from its original direction after penetrating the sur-