There's enough evidence that variation in sexual orientation is more a function of genes than of environment and for that reason alone, it should be accepted as but another example of human variability.

The idea of childhood as a social invention, in retrospect, is hardly credible. In the Bible, in writings of the Greeks and Romans, and in the works of the first great educator of the modern era, Comenius, children were recognized as being both different from adults and different from one another with respect to their stages of development. To be sure, the scientific study of children and the increased length of life in modern times have enhanced our understanding of age differences, but they have always been acknowledged.

Sigmund Freud was once asked to describe the characteristics of maturity, and he replied: lieben un arbeiten ("loving and working"). The mature adult is one who can love and allow himself or herself to be loved and who can work productively, meaningfully, and with satisfaction.

If learning to read was as easy as learning to talk, as some writers claim, many more children would learn to read on their own. The fact that they do not, despite their being surrounded by print, suggests that learning to read is not a spontaneous or simple skill.

Play is not only our creative drive; it's a fundamental mode of learning.

In leading-edge companies like Google and Apple, workers are given much freedom and opportunity to play. They know that's an important component of creating new and better products. I believe that at whatever level of work, cashier at a supermarket, janitor at an airport, aide in a cubicle, the addition of a playful attitude makes the job better and the work more enjoyable. A cashier or janitor who smiles and is friendly gets a better response than a surly one.

Friendships in childhood are usually a matter of chance, whereas in adolescence they are most often a matter of choice.