Matthew Yglesias

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.

If we live a self-directed, self-motivated, self-centered life, always needing to get our own way, then we're going to be miserable. In fact, many times we believe it's our problems that are making us unhappy when, in reality, it's because we're focused on ourselves!