For when we seek to press forward on our own account and increase our knowledge of this new fi eld, we lack the data of the natural standpoint, natural objects in particular, which through long-standing experience and the thought-practice of millenniums have become thoroughly familiar through their various distinctive properties, their elements, and their laws. Here the unknown still borders on the known. All methodical labour attaches itself to fact, all improvements of method to methods already in use; our concern generally is merely with the developing of special methods which fi t in with the already prescribed and well-established requirements of an approved scientifi c canon of method in general, and in the work of discovery they take their lead from these requirements.