These reflections, on the relationship between mathematics and its applications, were recorded by Iris Runge after she had worked for seven years as a researcher at the Osram Corporation. They also serve as an appropriate preamble to a conclusion of this book that should be claimed in advance: Iris Runge constructed mathematical bridges between various fields and can thus be regarded as a forerunner of the presently thriving disciplines of business and industrial mathematics.2 The purpose of this introduction is to outline the methodological considerations that will inform the subsequent chapters.