Projective geometry is all geometry.

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.

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

Projective geometry is all geometry.

But be that as it may, I think it is more respectful to you that I should speak to you upon and do my best to interest you in the subject which has occupied me, and in which I am myself most interested.

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

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