I found the link (click the title above) by this blog unschooling.com
"Parents bought mobiles, flash cards. The governors of Georgia and Missouri gave mothers of newborns classical music tapes and CDs because research seemed to indicate music would make babies smarter. And while this fervent interest in the brain development of little children swept through the nation, neuroscientists and others began to set the record straight about what neuroscience really had to say about enriched environments and critical periods.
"Cautioning against using monkey and rat research, Dr. William Greenough argued that the "rich" environment for a rat is actually the normal environment for a child. Infants are never raised completely alone and they often have much to explore right at home -- just crawling around the floor might bring a baby to table legs, books to be pulled out of bookshelves, clothes hampers to be upended. His research, stated Greenough, did not argue for extra stimulation. There was no research at all indicating that those mobiles, flash cards, and music lessons created more synapses in a baby's brain."
This seems to support what I've felt to be true intuitively. I remember when Aidan was just short of three, I was brought to tears by his developmental evaluator (who no doubt meant well; this is not a rant in the least). He said that Aidan had the potential to make lots of progress, but he would need a "thousand times" the stimulation of a normal child. Ugh! I could hardly bear the thought. My mental picture was of constantly prodding a rat through a labyrinth.
I notice sometimes in reading Montessori and Charlotte Mason, this sense of urgency, that if you miss some window, you can not make it up. Montessori more than CM; CM said that even a deprived child from an impoverished environment could make tons of progress in her type of schooling method.
The solution to me seems to be "opportunity" perhaps another word for "strewing".
I don't think there's anything wrong with playing classical music to infants by the way! Research also indicates that neonates whose moms have listened to classical music during the pregnancy respond to it while neonates whose moms watch soap operas tend to respond to the familiar soap opera sounds.