At some point, he accidentally acquires an ability that both saddens and comforts him: invisibility. This is a very awkward stealth technique: you must hold one hand on something rooted in the ground, then lift one foot off the ground, and use the other hand to grab the lifted foot from the back of the thigh.
In an instant, the whole person will be invisible.
No one can see him, and he can't see himself.
There is another person who also has a different ability: that is, he can see the steps extending to the sky from the air... And this person can go up along the steps.
This is a mind-bending book.