Like so many other things, I stumbled upon this - or into this - accidentally.
One day, feeling a bit put out, I just looked up and saw, much to my astonishment, the walls of the hole ascending far above me - and there, far away, at the top, a blur of light - the surface, from which I had so precipitously and unconsciously fallen.
Holy shit!, I thought, this is the same thing that happened to me yesterday! And the day before. And the day before that. Oh, wait - no, not the day before that - I don't think I fell into the hole on that particular day. The sense of displacement, disorientation, disconnection - entirely absent that day. Well, la di dah. What a great day that was. Yeah.
Anyway, not to be flippant, but... really - I was stunned. This explained so much! Why hadn't I noticed this before? Surrounded by walls, steep, clammy, unscalable - and I moseyed along as if everything was straightforward, a-ok, copacetic... No wonder things just haven't seemed to add up lately.