## Felix Klein (1849 - 1925)

The definition of *e* is usually, in imitation of the French models, placed at the very beginning of the great text books of analysis, and entirely unmotivated, whereby the really valuable element is missed, the one which mediates the understanding, namely, an explanation of why precisely this remarkable limit is used as a base and why the resulting logarithms are called natural.

*Elementary Mathematics from an Advanced Standpoint*