In Of Truth of Water, Ruskin suggests that Turner's water allows for the eye to behave as it does in nature, that is, with its default mode of focus seeing the duckweed, with reflections of sky and trees vague and indistinct. In painting Ruskin derides, he explains that these artists paint their waters in such a way as to force, in spite of themselves, the eye into (or approximate such focus, that is, to paint as if the eye has itself focused these images)seeing clearly reflections of sky and trees. Ruskin suggests this is false, but it seems rather to be the simple opposite of Turner. There being two "efforts" which the eye can shift between (or, it is that the eye is normally relaxed in a state which is prepared to observe near rays clearly), Turner approximates the visual equivalent of observing clearly objects on the water's surface; this is not the same as our choosing, by effecting the eye into the mode which receives these short or long rays, to observe the surface, as Ruskin reminds one may do in nature. Turner does not give us the choice, he has chosen for us the short view, the observing clearly objects on the surface, opposed to reflections. One cannot choose to effort the eye into observing distinctly these reflections, as one can in nature, yet as one can in such paintings as Ruskin derides. There of course we are neither choosing to observe clearly the water's reflections, but have had this mode of perception forced upon us, no differently as in Turner except that it is its opposite. A point for Turner's water may be had in that it presumes of the two effects of the eye that which is natural to it, i.e. that with which it defaultingly engages water in nature, but this seems not to be as substantial a point as Ruskin makes it out to be. A second may be had in Turner's greater control of the painting, in that he does not in spite of himself paint water in the short-effort of the eye, but purposefully anticipates the eye which has been concentrated in this mode. Turner chooses to paint in such a way, while the other artist, painting in the manner which supposes the opposite effort being present in the eye, does so accidentally, of his own incompetence. Again, this seems not so substantial a difference in that the two results are mere opposites, whatever their more or less intentioned conceptions.
A problem is apparent to me now in making clear reflections of sky and trees, that being surface objects would be similarly clear, suggesting of the eye two efforts simultaneously and a perception of nature which is not in reality possible, only in painting. So, while the bad artist gives an incompatible illusion of things near and far off, and Turner paints clearly surface objects and vaguely sky and trees, it is yet not possible to create the illusion of the long-ray effort of the eye; could one paint sky and trees clearly, leaving surface objects distorted, as is perceived with that effort of the eye in nature? Though Ruskin explains how in nature one alternates freely between these two modes of seeing, perceiving either but not both surface objects or distant objects distinctly, it is not apparent one could reproduce the efforted version of seeing which makes clear the reflection of distant objects, with its adverse effect upon a water's surface, in painting.