A quotation by Sofia Kovalevskaya

Say what you know, do what you must, come what may.
[Motto on her paper "On the Problem of the Rotation of a Solid Body about a Fixed Point."]

It is impossible to be a mathematician without being a poet in soul.

Many who have had an opportunity of knowing any more about mathematics confuse it with arithmetic, and consider it an arid science. In reality, however, it is a science which requires a great amount of imagination.