Trepanation as a focus comes in waves of intensity and direction. When I imagine being trepanned in a practical sense, the hole is very small, perhaps the size of the tip of a pen. It's just large enough that, were I to probe, I could feel the outline of it beneath the closed skin of my forehead. I see it as the cure to a natural fault. But when I imagine it from a less grounded perspective, the hole is much larger and I'm allowed constant access. It's a space to fill.
There was a shift in size a while ago - predictably, the resting state of the hole became just wide enough to take in a marble (about 20mm across). The ruminatory focus was to freeze a marble until its color became dulled by frost, then slip it inside of myself and feel its coldness become warmed by the folds of my brain. At times this extended to the glass heating into molten streams that cooled and re-hardened into a fragile, interior web.
I like to give Arthur impossible features that I'm envious of. His own bore holes are neither immutable nor fixed. They can be open to the air and vary in both number and size. They can stretch enough that I could spread one apart to kiss his brain and feel the blood pulse beneath my lips; or the man with the painted face could do the same, but with his tongue and his fingers. Arthur could shove objects deep inside himself, into this space that constantly craves access.
It is interesting how one incessant desire can simply absorb all other desires. In a way, it seems necessary, and perhaps universal - a natural part of human functionality. A specific form of endocytosis.