What is a miracle? Webster's dictionary defines a miracle as an "extraordinary event manifesting divine intervention in human affairs." More colorfully and memorably, C. S. Lewis once explained that a miracle is something unique that breaks a pattern so expected and established we hardly consider the possibility that it could be broken. "If for thousands of years," he said, "a woman can become pregnant only by sexual intercourse with a man, then if she were to become pregnant without a man, it would be a miracle."

The skeptic and philosopher David Hume spoke famously against miracles but defined them as "a transgression of a law of nature by a particular volition of the Deity, or by the interposition of some invisible agent." We can basically agree with Hume on this definition, which is probably as close to a standard definition as we will be able to settle on. But I would further simply say that it is when something outside time and space enters time and space, whether just to wink at us or poke at us briefly, or to come in and dwell among us for three decades.