It might be worth mentioning that this story, seemingly so sterile, illustrates well how wrenchingly visceral Cordwainer Smith can be -- a salient point here is that he had struggled throughout his life with one missing eye and poor vision in the other. This meant that he was often entirely without sight for a good deal of time...quite a handicap for someone in military intelligence and diplomacy, as he was.

Scanners, on the other hand have no senses other than sight, and not only must check heart rate on a regular basis but must check against bodily harm. They can feel emotion, but don't have any clue as to what their faces are doing.

Armed with this knowlege it's interesting to see how he inverts his experience to make the "Scanners" more real. Scanners use mirrors to make sure that everything is OK with their bodies...just as he probably utilized every reflective surface in sight to make up for lack of direct vision on one side. One of the Scanners can control his face to suit his emotion, which he learned from hard practise, again, with mirrors -- just as one of his signature photos shows him giving a roguish look...with his glass eye.

I don't know if this is too fannish, but it is interesting.