Reception of Photons in the Eye: Rods and Cones
Photons enter the eye and strike rods and cones
Which contain photo-pigment molecules.
These molecules are the agents of vision;
they transduce photons into nerve impulses
by a chemical reaction to the impact
that straightens an amino acid chain.
The molecule then twitches or twists,
making vision a form of touch –
Photons of light touch sensitive molecules.
The rods perceive intensity of light, and
cones perceive the various wavelengths.
There are normally 3 types of cones, sensitive to 3 frequencies:
BLUE: blue-violet short wavelengths
GREEN: green medium wavelengths
RED: orange-red long wavelengths
These three are not evenly spaced across the spectrum.
‘Green’ and ‘red’ cones are sensitive to similar light waves.
It takes at least two cones,
sensitive to different bands of wavelength,
to provide information that the brain interprets as colours.
Red and Green
Defects in red-green vision are sex linked, because …
the gene for blue-violet is located on chromosone seven,
but the red and green genes are near each other on the X (sex) chromosone
Detail and Night Vision
Greatest visual clarity is the fovea, which is where there are the most cones.
Cones are specifically colour sensitive
and individually connected to others,
so stimuli to each cell are reproduced directly
and fine details can be distinguished.
Rods are sensitive to overall illumination,
and connected in groups,
and respond to stimuli generally; not separating small details.
Dim objects are better seen in peripheral vision.
Biological Evolution of the Eye; past and future
Each colour-sensitive cone developed for different purposes.
Green genes were probably the first to develop.
Secondarily, the ‘red’ sensitive cone gene,
were believed to have co-evolved with a class of tropical trees that had fruits,
too large for birds, and were yellow, orange or red when ripe (apples, oranges, , etc.)
The vegetable kingdom was offering information of ripeness
to animals that can distinguish warmer colours.
We share spatial and ‘normal’ tri-chromatic vision with Old World monkeys and apes.
Tri-chromatic cones may be the exception and not the rule.
There is not concensus: tetrachromats (4 cones) is not unlikely in humans.
A 4th cone (called "orange") sensitive to wavelengths longer than “Red”,
might be present in up to 50% of women and 10% of men.
There is a “warm bias” in the photoreceptor cells,
despite the logic that evolution would have developed sensitivity
in the blue of mid-day
(Ultraviolet wavelengths are harmful for longer-lived mammals with large eyes;
The primate eye may therefore be adapted in part to shift away from UV light.)
Conjecture on Etheric Perception and EM Spectrum
Sensitivity to blue-violet does not appear to be evolutionarily crucial,
There are very few cones in this area of sensitivity
Letters on Occult Meditation p. 208
Green is the foundational colour of nature, and upon it blue is built.
We are (esoterically) in the second or ‘blue’ solar system,
Blue-violet could relate to sensitivity to 2nd ray or love-wisdom energy,
as opposed to the mass under 1st or 3rd (green ‘solar system’) sensitivity.
However, this is not born out exoterically.
The “warm bias” in suggests an increasing sensitivity to reds.
This could relate to humanity becoming more accustomed to the impact of the will, monadic, or Shamballic ‘frequencies’ this would correlate with sensitivity to the red system
But if, (as DK suggests) we are racially developing etheric vision,
and this is a function of the physical eye,
then the ‘etheric spectrum’ must be somewhere in the EM spectrum
(or what is the alternative? Is there a more subtle spectrum that ‘overlaps’?):