Hmmm...No worthwhilewind I don't think this crew quite ready to seek nirvana, instead I think they need a koanic jolt to their modern day romote-clicking television sensibilities so that they might begin to understand the strange world that exists around them so that once again they can walk as equals among free thinking men.

Ah what the hell, let's try it anyway. (WO'N this extends your point about indirect viewing.)

*** Astronomers have learned that they can see very dim stars if they don't look directly at them. Sailors also know that this is the best way to see a dim light and use this technique of "averted vision". It works because the fovea contains only cones, which require a higher level of light than the rods, even though they distinguish color and images. The rods, exquisitely sensitive to even the lowest levels of light, are distributed around the fovea. To use them best, the eye must not aim directly at the object to be viewed. Thus to make out a dim pinpoint against the background of the night sky, the rods work best, and they are not in the fovea at all but spread around the central region of the retina.

*** During November in 1992 I studied the habits of blackbirds. In particular a flock (700 +) that nested at night in a huge magnolia tree in downtown Birmingham. At first light, after a warming spell on the nearby electric wires, the flock would fly (two to eight miles) towards the rising sun to neighborhood feeding grounds, separating into bird units of one, twos, threes, fours, or fives .
Then late in the afternoon they would begin to gather into long high flying bands, now flying westward towards the setting sun. Then upon arrival at the magnolia tree they would alight on the electric wires and warm their feathers and wait until someone or something, decided it was time to go to bed. Who or what decided, was my quest. I never did find out, but each time, at a point before the sun fully set, in an instantaneous flapping rush of 1,400 wings, the electric wires were emptied and the magnolia tree became full and the magnolia tree became dark and still for the night.
The rush to the tree took less than three seconds, and it was always complete to the last bird; no stragglers arrived after the single rush. I knew then of the green flash but never saw it, but now I suspect the trigger was a blue (or violet) flash that is unavailable for seeing by the unaided human eye .

*** The next time you go to the supermarket to check out the apples or peaches, turning them over to look for bruises or spoilage, remember that you are using your color vision in the same way your distant forebears did.
You will also be using your stereoscopic vision, the ability to focus both your eyes on the same spot in order to determine depth or distance. Stereoscopic vision must have been an important asset for creatures that lived in high trees, where missing a branch as you swung home could mean a screaming, fatal fall.
Those days of tree dwelling must have left an indelible imprint on our minds. The three most common fears among humans are fear of darkness, fear of falling, and fear of snakes. To a tree dwelling animal, darkness meant danger unless it was safely bundled into a warm, cozy nest. You can not see where you are going in the dark, and even our early ancestors depended heavily on vision; they were diurnal (daylight active) creatures, not nocturnal animals. Fear or falling is obvious to a tree-dwelling species. Infants display an innate fear of heights at the age of only a few months. And snakes must have been one of the few predators that could reach our monkey ancestors up in their leafy nests. Even in the dark. ~ Ben Bova ~ Story of Light

Conclusion

The rising and setting sun triggered directional and vital temporal responses in early man. Genetic amplification of the external signal of the sun (and to a lessor extent, the moon) to a image greatly magnified, was so advantageous to our predecessors that today, try as we might, our mind/eye system won't allow us to see the sun or the moon on the horizon, any other way.