I must have an odd faith in humanity if it can be boosted by watching the wonder on the faces of my students after I showed them how to have their calculators (TI-83s in most cases) display parametric curves and Lissajous figures.

There’s something mesmerizing about the little cursor moving across the screen like a wasp around a hive. And with the right set of k values (or is it w values) you can get spirograph-like figures on your display.