Geometry with pen.

Yes, I do question myself sometimes. I care little for erasers. I know they have their place, especially in architectural drafting, mathematics, and beginning forgery.

But there is also something so brave and bold and reckless about embarking on a trigonometric journey or geometric odyssey armed with only a pen, a leaky pen, a gel pen that will under no circumstances be unmarked or removed from the historical record once its mark has been made. There is a beauty in that, and there is a beauty to watching applied mathematics get applied in exciting new ways.

And thus are discoveries made.

Like I said, I do question myself sometimes. But then I smile with pride at our little mathematician, looking around for an eraser, finding none (thank goodness), and blazing into the unknown territories that Euclid, Newton, Riemann were afraid to enter. We do the dangerous thing, son, we do the dangerous thing.