\begin{quote}
{\noindent
{\em Sagredo}: ... I cannot believe that the action of light,
however pure, can be without motion, and indeed the swiftest.

{\em Salviati}: But what and how great should we take the speed
of light to be?
Is it instantaneous perhaps, and momentary?
Or does it require time, like other movements?
Could we assure ourselves by experiment which it may be?

Galileo Galilei \index{author: Galileo}(1564-1642)\\
{\em Two New Sciences} (1638)\\
page 49 of Stillman Drake's \index{author: Drake, Stillman}
translation of \cite{Galileo:1638}\\}
\end{quote}