When two parallel lines intersect (#2 in some “classic posts” about writing)…

I shook the mathematical beliefs of my thirteen-year-old niece the other afternoon. An elementary problem in algebra required knowing that the measures of the interior angles in a triangle sum to 180 degrees. That’s in Euclidean geometry. [She’s sixteen now and through geometry too.] I commented that there are other non-Euclidean geometries where that “rule” is not true. In one of these geometries, parallel lines can meet.

Many of you might be yawning now, I suppose, but there’s a message abou...