We are a fluke of nature, a quirk of evolution, a glorious contingency.

Science is not the affirmation of a set of beliefs but a process of inquiry aimed at building a testable body of knowledge constantly open to rejection or confirmation. In science, knowledge is fluid and certainty fleeting. That is at the heart of its limitations. It is also its greatest strength.

In comparison, Google is brilliant because it uses an algorithm that ranks Web pages by the number of links to them, with those links themselves valued by the number of links to their page of origin.

Through no divine design or cosmic plan, we have inherited the mantle of life's caretaker on the earth, the only home we have ever known.

To be a fully functioning moral agent, one cannot passively accept moral principles handed down by fiat. Moral principles require moral reasoning.

Flawed as they may be, science and the secular Enlightenment values expressed in Western democracies are our best hope for survival.

The actual atoms and molecules that make up my brain and body today are not the same ones that I was born with on September 8, 1954, a half-century ago this month.