Shape

258 II Seeing How It Works
—and subtraction rules, as well—in which right sides contain a single point or several
of them to show where rules apply next. New rules are always worth a try. With mine,
I can get shapes like this
Let’s look at something else—maybe rectangles and squares that keep their size
and line up edge to edge and vertex to vertex in these spatial relations
defined in my kindergarten rhyme. Points help to take advantage of the symmetries,
and lined paper makes drawing easy. Try it.
Zero-dimensional devices help to tame rules in higher-dimensional algebras. In
particular, points and lines show how visual ideas can be controlled in a comfortable,