## A quotation by Jacques Hadamard

The shortest path between two truths in the real domain passes through the complex domain.

Quoted in

*The Mathematical Intelligencer*

**13**(1991).

Practical application is found by not looking for it, and one can say that the whole progress of civilization rests on that principle.

Quoted in H Eves

*Mathematical Circles Squared*(Boston 1972).

To parents who despair because their children are unable to master the first problems in arithmetic I can dedicate my examples. For, in arithmetic, until the seventh grade I was last or nearly last.

Quoted in D MacHale,

*Comic Sections*(Dublin 1993)

Logic merely sanctions the conquests of the intuition.

Quoted in M Kline,

*Mathematical thought from ancient to modern times*(New York, 1972).

Can the existence of a mathematical entity be proved without defining it ?