In his brilliant new book, Catching the Light, quantum physicist Arthur Zojanc writes of what he describes as the "entwined history of light and mind" (correctly described by one admirer as the "two ultimate metaphors of the human spirit"). For our purposes, his initial chapter is most helpful.
From both the animal and human studies, we know there are critical developmental "windows" in the first years of life. Sensory and motor shills are formed, and if this early opportunity is lost, trying to play catch up is hugely frustrating and mostly unsuccessful.
Prof. Zajoc writes of studies which investigated recovery from congenital blindness. Thanks to cornea transplants, people who had been blind from birth would suddenly have functional use of their eyes. Nevertheless, success was rare. Referring to one young boy, "the world does not appear to the patient as filled with the gifts of intelligible light, color, and shape upon awakening from surgery," Zajoc observes. Light and eyes were not enough to grant the patient sight. "The light of day beckoned, but no light of mind replied within the boy’s anxious, open eyes."
Zajoc quotes from a study by a Dr. Moreau who observed that while surgery gave the patient the "power to see," "the employment of this power, which as a whole constitutes the act of seeing, still has to be acquired from the beginning." Dr. Moreau concludes, "To give back sight to a congenitally blind person is more the work of an educator than of a surgeon." To which Zajoc adds, "The sober truth remains that vision requires far more than a functioning physical organ. Without an inner light, without a formative visual imagination, we are blind," he explains. That "inner light" -- the light of the mind -- "must flow into and marry with the light of nature to bring forth a world."
National Right to Life News, March 30, 1993, p. 22.