Claude Monet developed cataracts late in life. Edgar Degas suffered from an eye disease that warped his central vision. An article at LiveScience.com The Blurry World of Claude Monet Recreated details the efforts of Stanford ophthalmologist Michael Marmor to discover through computer manipulation of images how these painters' failing vision might have affected their work.

According to Marmor, as Monet began to see the world in a monotone some of his paintings displayed uncharacteristically strong colors.

"Monet may have used strong colors in these paintings because he was only using them from memory, picking colors by the name on the paint tubes, or because he was overcompensating for his yellow vision by adding more blue...So his vision was becoming progressively more brownish in essence....It was getting harder to see, it was getting blurrier, but he was probably more bothered by the progressive loss of color vision than the blur alone."

In the case of Degas:

"...as his vision steadily blurred, the outlines and shading of his work became coarser and more irregular and fine details were lost.

"But to him, the blur smoothed out this coarseness, so the form of the subject, which was his focus, looked similar to his earlier works, according to Marmor's computer manipulations. So it is possible that he was unaware of how the later paintings appeared to others.

"But friends, family and art critics noticed the dramatic change from his earlier works, and pointed it out to Degas."

Marmor concludes:

"I think it does not say that the paintings are good or bad or answer to the question as to how much they were trying to change their style...But I think it points out very dramatically some physical limitations that they had, which both limited their ability to paint, to put paint on canvas directly, but also to interpret what they were putting on a canvas-they couldn't really judge what they were seeing."

We often speak of an artist's "vision." But, to an extent, this vision is beyond the artist's control and he or she may not be entirely aware of its effect on the audience.

Writers don't try to reproduce the effect of light on their retinas by placing pigments on canvas which, they hope, will have a similar as that light effect on viewers. But we do try to capture what we see in words and so can inadvertently capture our own idiosyncratic perceptions.

For example, until it was pointed out to us, Mary and I never realized that in all the mystery stories and novels we have written, the culprit, once unmasked, is seldom turned over to the authorities. Almost invariably, it is the investigator who administers appropriate justice, not always of the Mike Hammer bullet-in-the-belly kind.

This is probably because, in the world I see, government institutions wouldn't recognize justice if they tripped over it and, perhaps more importantly, do not, to my way of thinking, possess the moral authority to mete out justice anyway. So, for me, an ending where the villain was handed over to a criminal justice system would be highly unsatisfying.

The endings we paint look right to me, but perhaps to a typical reader, due process would look better.