Euler, Riemann, Hirzebruch

Euler was the great magician who could conjure up beautiful formulae, and he was followed by
Riemann who devised analytical methods to justify them.  In the 20th century Hirzebruch was the
magician who carried on their work with ideas which he and his colleagues developed in Bonn
50 years ago. In the 21st century we are rediscovering the power and beauty of these methods.
I will discuss what can be found hidden in the mathematics of the past, a new kind of magic.