One service mathematics has rendered the Et moi ... si j avait su comment en revenir je n y serais point aile. human race. It has put common sense back Jules Verne where it belongs on the topmost shelf next to the dusty canister labelled discarded n- sense . The series is divergent; therefore we may be able to do something with it. Eric T. Bell O. Heaviside Matht natics 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 seNe 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 d etre of this series.