THE AGE OF THE WORLD PICTURE
to stand and yet allow the motion to remain a motion. The fixedness of the facts and the constancy of their change as such is the rule. The constancy of change in the necessity of its course is the law. Only from the perspective of rule and law do facts become clear as what they are. Research into the facts in the realm of nature is the setting up and confirmation of rule and law. The method by means of which a domain of objects is represented has the character of a clarification [Klärung] from out of the clear, of explanation [Erklärung]. Explanation always has two sides to it. It accounts for something unknown through something known, and at the same time confirms the known through that unknown. Explanation takes place in investigation. In the natural sciences this happens in the experiment, always according to the nature of the field of investigation and the kind of explanation aimed at. However, natural science does not first become research through experiment. It is rather the other way round: experiment is only possible where knowledge of nature has already transformed itself into research. It is only because contemporary physics is a physics that is essentially mathematical that it is capable of being experimental. Since neither the medieval doctrina nor the Greek ἐπιστήμη were science in the sense of research, there was, for them, no question of experiment. To be sure, Aristotle was the first to grasp the meaning of ἐμπειρία (experientia): the observation of the things themselves, their characteristics and alterations under changing conditions, resulting in knowledge of the way in which they behave as a rule. But observation directed toward knowledge of this kind, the experimentum, is essentially different from that which belongs to science as research, the research-experiment. It remains essentially different even where ancient and medieval observation also works with number and measure, and even where it makes use of specific apparatus and instruments. For what is completely absent here is what is decisive about the experiment. This begins with the fundamental postulation of a law. To set up an experiment is to represent a condition according to which a specific nexus of motions can become capable of being followed in its necessary course, which is to say that it can be mastered, in advance, by calculation. The setting up of the law, however, is accomplished with reference to the ground-plan of the sphere of objects. This provides the standard and constrains the anticipatory representation of the condition. Such representing with and within which the experiment begins is no arbitrary invention. This is why Newton says hypotheses non fingo; the fundamental postulations are not arbitrarily thought up. They are, rather, developed out of the ground-plan of nature and are sketched into it. Experiment is that method which,
61