Complete knowledge of the nature of an analytic function must also include insight into its behavior for imaginary values of the arguments. Often the latter is indispensable even for a proper appreciation of the behavior of the function for real arguments. It is therefore essential that the original determination of the function concept be broadened to a domain of magnitudes which includes both the real and the imaginary quantities, on an equal footing, under the single designation complex numbers.

Mathematical discoveries, like springtime violets in the woods, have their season which no human can hasten or retard.

His second motto: Thou, nature, art my goddess; to thy laws my services are bound.

When a philosopher says something that is true then it is trivial. When he says something that is not trivial then it is false.

It is always noteworthy that all those who seriously study this science [the theory of numbers] conceive a sort of passion for it.

Theory attracts practice as the magnet attracts iron.

Mathematics is the queen of the sciences.