\section{Global, local, infintesimal}

An over-riding theme in geometry and topology is the connection between the
global, local, and infintesimal pictures.

(talk about sheaves, and stalks (one can differentiate germs!),
 and how global -> local -> infintesimal is generally easy,
 while other way is -hard- and interesting
 (eg of f' = 0 => constant, gauss-bonet, etc.)

