Et moi ..... si j'avait su comment en revenir, One service mathematics bas rendered the je n'y serais point aile: human race. It bas put common sense: back Jules Verne where it belongs, on the topmost shelf next 10 tile dusty canister labelled 'discarded 1lOII- The series is divergent, thCldorc we may be ICDIC'. able 10 do something with it. Eric T. Bell O. Heaviside 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 d'!tre of this series.