  Particular families of special functions, conceived as purely mathematical
devices between the end of XVIII and the beginning of XIX centuries, have
played a crucial role in the development of many aspects of modern Physics.
This is indeed the case of the Euler gamma function, which has been one of the
key elements paving the way to string theories, furthermore the Euler-Riemann
Zeta function has played a decisive role in the development of renormalization
theories. The ideas of Euler and later those of Riemann, Ramanujan and of
other, less popular, mathematicians have therefore provided the mathematical
apparatus ideally suited to explore, and eventually solve, problems of
fundamental importance in modern Physics. The mathematical foundations of the
theory of renormalization trace back to the work on divergent series by Euler
and by mathematicians of two centuries ago. Feynman, Dyson, Schwinger...
rediscovered most of these mathematical "curiosities" and were able to develop
a new and powerful way of looking at physical phenomena.
