what, for the sought-after knowledge of nature, is henceforth to count as "nature": the closed system of spatio-temporally related units of mass. Pertaining to this ground-plan, in accordance with its prior specification, are to be found, among others, the following definitions. Motion is change of place. No motion or direction of motion takes precedence over any other. Every point is equal to every other. No point in time has precedence over any other. Every force is defined as -- is, that is, nothing but -- its consequences as motion within the unity of time; and that means, again, change of place. Every natural event must be viewed in such a way that it fits into this ground-plan of nature. Only within the perspective of this ground-plan does a natural event becomes visible as such. The ground-plan of nature is secured in place in that physical research, in each step of investigation, is obligated to it in advance. This obligation, the rigor of research, has, at a given time, its own character in keeping with the ground-plan. The rigor of mathematical science is exactitude. Every event, if it enters at all into representation as a natural event, is determined, in advance, as a magnitude of spatio-temporal motion. Such determination is achieved by numbers and calculation. Mathematical research into nature is not, however, exact because it calculates precisely; rather, it must calculate precisely because the way it is bound to its domain of objects has the character of exactness.

Science becomes research through the projected plan and through the securing of the plan in the rigor of procedure. Projection and rigor, however, first develop into what they are in method. Method constitutes the second essential characteristic of research. If the projected region is to become objectified, then it must be brought to encounter us in the full multiplicity of its levels and interweavings. Procedure must therefore be free to view the changeableness in what it encounters. Only from within the perspective of the ever-otherness of change does the plenitude of the particular, of the facts, reveal itself. The facts, however, are to become objective. Procedure must, therefore, represent the changeable in its changing; it muo;t bring it