Ted Danson

If you take one rivet out of an airplane, it will be all right, it'll keep flying. You take another rivet out of the airplane and it still flies. So what the heck, let's take more rivets out of the airplane, and sooner or later, the airplane drops from the sky.

Innate mechanisms endow the visual system with highly specific connections, but visual experience early in life is necessary for their maintenance and full development. Deprivation experiments demonstrate that neural connections can be modulated by environmental influences during a critical period of postnatal development.