As for everything else, so for a mathematical theory: beauty can be perceived but not explained.

And in another point of view, I think it is right that the address of a president should be on his own subject, and that different subjects should be thus brought in turn before the meetings.

Projective geometry is all geometry.

Euclid avoids it [the treatment of the infinite]; in modern mathematics it is systematically introduced, for only then is generality obtained.

So much the worse, it may be, for a particular meeting: but the meeting is the individual, which on evolution principles, must be sacrificed for the development of the race.

Metrical geometry is thus a part of descriptive geometry, and descriptive geometry is all geometry.

As for everything else, so for a mathematical theory: beauty can be perceived but not explained.