One service mathematics has rendered the ""Et moi, .... si jaait su comment en revenir, human race. It has put common sense back je ny scrais point alit: Jules Verne where it belongs, on the topmost shelf next to the dusty canister labcled discarded non- The series is divergent; therefore we may be sense. Eric T. 8cl able to do something with it. O. Hcaviside Mathematics is a tool for thought. A highly necessary tool in a world where both feedback and non- linearities abound. Similarly, all kinds of parts of mathematics serve as tools for other parts and for other sciences. Applying a simple rewriting rule to the quote on the right above one finds such statements as: One service topology has rendered mathematical physics .. .; One service logic has rendered com- puter science .. .; One service category theory has rendered mathematics .. .. All arguably true. And all statements obtainable this way form part of the raison detre of this series.