MacTutor
The shortest path between two truths in the real domain passes through the complex domain.
Practical application is found by not looking for it, and one can say that the whole progress of civilization rests on that principle.
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.
Logic merely sanctions the conquests of the intuition.
Can the existence of a mathematical entity be proved without defining it ?