The aim of this book is to construct categories of spaces which contain
all the C?-manifolds, but in addition infinitesimal spaces and arbitrary
function spaces. To this end, the techniques of Grothendieck toposes
(and the logic inherent to them) are explained at a leisurely pace and
applied. By discussing topics such as integration, cohomology and vector
bundles in the new context, the adequacy of these new spaces for
analysis and geometry will be illustrated and the connection to the
classical approach to C?-manifolds will be explained.