A mathematical problem should be difficult in order to entice us, yet not completely inaccessible, lest it mock at our efforts. It should be to us a guide post on the mazy paths to hidden truths, and ultimately a reminder of our pleasure in the successful solution.

One must be able to say at all times--instead of points, straight lines, and planes--tables, chairs, and beer mugs

Wir mussen wissen. Wir werden wissen. We must know. We will know. Inscribed on his tomb in Gilttingen.

For us there is no ignorabimus, and in my opinion none whatever in natural science. In opposition to the foolish ignorabimus our slogan shall be: "We must know - we will know!"

Mathematics knows no races or geographic boundaries; for mathematics, the cultural world is one country.

He who seeks for methods without having a definite problem in mind seeks in the most part in vain.

Geometry is the most complete science.