The Blind and the Lame
The blind needs a pair of eyes and the lame needs a pair of legs, so let them live together. The blind lives in the middle of the ramp and the lame lives outside.
The blind helps the lame to push his wheelchair to the roof at 16:00 every day. The lame cannot go upstairs by himself and his daily life is a process keeping declining on the ramp. Time leaves a trace in space.